Point cloud data transmission device, point cloud data transmission method, point cloud data reception device, and point cloud data reception method

ABSTRACT

Disclosed herein are a point cloud data transmission method including encoding point cloud data, and transmitting point cloud data, and a point cloud data reception method including receiving point cloud data, decoding the point cloud data, and rendering the point cloud data.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.63/008,670, filed on Apr. 11, 2020, and 63/010,066, filed on Apr. 15,2020, which are hereby incorporated by reference as if fully set forthherein.

TECHNICAL FIELD

Embodiments provide a method for providing point cloud content toprovide a user with various services such as virtual reality (VR),augmented reality (AR), mixed reality (MR), and self-driving services.

BACKGROUND

A point cloud is a set of points in a three-dimensional (3D) space. Itis difficult to generate point cloud data because the number of pointsin the 3D space is large.

A large throughput is required to transmit and receive data of a pointcloud.

SUMMARY

An object of the present disclosure is to provide a point cloud datatransmission device, a point cloud data transmission method, a pointcloud data reception device, and a point cloud data reception method forefficiently transmitting and receiving a point cloud.

Another object of the present disclosure is to provide a point clouddata transmission device, a point cloud data transmission method, apoint cloud data reception device, and a point cloud data receptionmethod for addressing latency and encoding/decoding complexity.

Embodiments are not limited to the above-described objects, and thescope of the embodiments may be extended to other objects that can beinferred by those skilled in the art based on the entire contents of thepresent disclosure.

To achieve these objects and other advantages and in accordance with thepurpose of the disclosure, as embodied and broadly described herein, amethod for transmitting point cloud data may include encoding pointcloud data, encapsulating the point cloud data, and transmitting thepoint cloud data.

In another aspect of the present disclosure, a method for receivingpoint cloud data may include receiving point cloud data, decapsulatingthe point cloud data, and decoding the point cloud data.

The point cloud data transmission method, the point cloud datatransmission device, the point cloud data reception method, and thepoint cloud data reception device according to the embodiments mayprovide a good-quality point cloud service.

The point cloud data transmission method, the point cloud datatransmission device, the point cloud data reception method, and thepoint cloud data reception device according to the embodiments mayachieve various video codec methods.

The point cloud data transmission method, the point cloud datatransmission device, the point cloud data reception method, and thepoint cloud data reception device according to the embodiments mayprovide universal point cloud content such as a self-driving service.

It is to be understood that both the foregoing general description andthe following detailed description of the present disclosure areexemplary and explanatory and are intended to provide furtherexplanation of the disclosure as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the disclosure andtogether with the description serve to explain the principle of thedisclosure. In the drawings:

FIG. 1 illustrates an exemplary structure of a transmission/receptionsystem for providing point cloud content according to embodiments;

FIG. 2 illustrates capture of point cloud data according to embodiments;

FIG. 3 illustrates an exemplary point cloud, geometry, and texture imageaccording to embodiments;

FIG. 4 illustrates an exemplary V-PCC encoding process according toembodiments;

FIG. 5 illustrates an example of a tangent plane and a normal vector ofa surface according to embodiments;

FIG. 6 illustrates an exemplary bounding box of a point cloud accordingto embodiments;

FIG. 7 illustrates an example of determination of individual patchpositions on an occupancy map according to embodiments;

FIG. 8 shows an exemplary relationship among normal, tangent, andbitangent axes according to embodiments;

FIG. 9 shows an exemplary configuration of the minimum mode and maximummode of a projection mode according to embodiments;

FIG. 10 illustrates an exemplary EDD code according to embodiments;

FIG. 11 illustrates an example of recoloring based on color values ofneighboring points according to embodiments;

FIG. 12 illustrates an example of push-pull background filling accordingto embodiments;

FIG. 13 shows an exemplary possible traversal order for a 4*4 blockaccording to embodiments;

FIG. 14 illustrates an exemplary best traversal order according toembodiments;

FIG. 15 illustrates an exemplary 2D video/image encoder according toembodiments;

FIG. 16 illustrates an exemplary V-PCC decoding process according toembodiments;

FIG. 17 shows an exemplary 2D video/image decoder according toembodiments;

FIG. 18 is a flowchart illustrating operation of a transmission deviceaccording to embodiments of the present disclosure;

FIG. 19 is a flowchart illustrating operation of a reception deviceaccording to embodiments;

FIG. 20 illustrates an exemplary architecture for V-PCC based storageand streaming of point cloud data according to embodiments;

FIG. 21 is an exemplary block diagram of a device for storing andtransmitting point cloud data according to embodiments;

FIG. 22 is an exemplary block diagram of a point cloud data receptiondevice according to embodiments;

FIG. 23 illustrates an exemplary structure operable in connection withpoint cloud data transmission/reception methods/devices according toembodiments;

FIG. 24 shows a patch, an atlas, an atlas tile group, an atlas frame,and the like;

FIG. 25 shows a structure of a bitstream containing point cloud dataaccording to embodiments;

FIG. 26 shows a structure of a bitstream containing point cloud dataaccording to embodiments;

FIG. 27 shows a V-PCC unit and a V-PCC unit header according toembodiments;

FIG. 28 shows the payload of a V-PCC unit according to embodiments;

FIG. 29 shows a V-PCC parameter set according to embodiments;

FIG. 30 shows an atlas frame according to embodiments;

FIG. 31 shows a structure of an atlas bitstream according toembodiments;

FIG. 32 shows a sample stream NAL unit, a sample stream NAL unit header,a NAL unit, and a NAL unit header included in a bitstream containingpoint cloud data according to embodiments;

FIG. 33 shows NAL unit types according to embodiments;

FIG. 34 shows an atlas sequence parameter set according to embodiments;

FIG. 35 shows an atlas frame parameter set according to embodiments;

FIG. 36 shows atlas_frame_tile_information according to embodiments;

FIG. 37 shows atlas_adaptation_parameter_set according to embodiments;

FIG. 38 shows atlas_camera_parameters according to embodiments;

FIG. 39 shows atlas_tile_group_layer and atlas_tile_group_headeraccording to embodiments;

FIG. 40 shows a reference list structure (ref_list_struct) according toembodiments;

FIG. 41 shows atlas tile group data (atlas_tile_group_data_unit)according to embodiments;

FIG. 42 shows patch_information_data according to embodiments;

FIG. 43 shows patch_data_unit according to embodiments;

FIG. 44 shows a V-PCC atlas relation box according to embodiments;

FIG. 45 shows a V-PCC global atlas information box according toembodiments;

FIG. 46 shows a dynamic atlas relation sample group and a dynamic globalatlas information sample group according to embodiments;

FIG. 47 shows an overview of a structure for encapsulating non-timedV-PCC data according to embodiments;

FIG. 48 illustrates a file encapsulation operation for multiple atlasdata according to embodiments;

FIG. 49 illustrates a file decapsulation operation for atlas dataaccording to embodiments;

FIG. 50 illustrates file level signaling according to embodiments;

FIG. 51 illustrates file level signaling according to embodiments;

FIG. 52 shows structures of a V-PCC bitstream and a V-PCC file formataccording to embodiments;

FIGS. 53, 54, and 55 show scene object information according toembodiments;

FIG. 56 shows object label information according to embodiments;

FIG. 57 shows patch information according to embodiments;

FIG. 58 shows volumetric rectangle information;

FIG. 59 shows hierarchy of an SEI message in an atlas sub-bitstreamaccording to embodiments;

FIG. 60 illustrates a configuration of an atlas tile group (or tile)according to embodiments;

FIG. 61 shows a VPCC spatial regions box according to embodiments;

FIG. 62 shows a VPCC spatial regions box according to embodiments;

FIGS. 63, 64, and 65 are flowcharts illustrating file encapsulationaccording to embodiments;

FIGS. 66 and 67 are flowcharts illustrating an operation of a filedecapsulator according to embodiments;

FIG. 68 illustrates file level signaling according to embodiments;

FIG. 69 illustrates file level signaling according to embodiments;

FIG. 70 shows an encapsulated V-PCC data container structure accordingto embodiments;

FIG. 71 shows a structure of a file according to embodiments;

FIG. 72 shows tracks according to the embodiments;

FIG. 73 illustrates a method of transmitting point cloud data accordingto embodiments; and

FIG. 74 illustrates a method of receiving point cloud data according toembodiments.

DETAILED DESCRIPTION Best Mode

Reference will now be made in detail to the preferred embodiments of thepresent disclosure, examples of which are illustrated in theaccompanying drawings. The detailed description, which will be givenbelow with reference to the accompanying drawings, is intended toexplain exemplary embodiments of the present disclosure, rather than toshow the only embodiments that can be implemented according to thepresent disclosure. The following detailed description includes specificdetails in order to provide a thorough understanding of the presentdisclosure. However, it will be apparent to those skilled in the artthat the present disclosure may be practiced without such specificdetails.

Although most terms used in the present disclosure have been selectedfrom general ones widely used in the art, some terms have beenarbitrarily selected by the applicant and their meanings are explainedin detail in the following description as needed. Thus, the presentdisclosure should be understood based upon the intended meanings of theterms rather than their simple names or meanings.

FIG. 1 illustrates an exemplary structure of a transmission/receptionsystem for providing point cloud content according to embodiments.

The present disclosure provides a method of providing point cloudcontent to provide a user with various services such as virtual reality(VR), augmented reality (AR), mixed reality (MR), and self-driving. Thepoint cloud content according to the embodiments represent datarepresenting objects as points, and may be referred to as a point cloud,point cloud data, point cloud video data, point cloud image data, or thelike.

A point cloud data transmission device 10000 according to embodiment mayinclude a point cloud video acquirer 10001, a point cloud video encoder10002, a file/segment encapsulation module 10003, and/or a transmitter(or communication module) 10004. The transmission device according tothe embodiments may secure and process point cloud video (or point cloudcontent) and transmit the same. According to embodiments, thetransmission device may include a fixed station, a base transceiversystem (BTS), a network, an artificial intelligence (AI) device and/orsystem, a robot, and an AR/VR/XR device and/or a server. According toembodiments, the transmission device 10000 may include a device robot, avehicle, AR/VR/XR devices, a portable device, a home appliance, anInternet of Thing (IoT) device, and an AI device/server which areconfigured to perform communication with a base station and/or otherwireless devices using a radio access technology (e.g., 5G New RAT (NR),Long Term Evolution (LTE)).

The point cloud video acquirer 10001 according to the embodimentsacquires a point cloud video through a process of capturing,synthesizing, or generating a point cloud video.

The point cloud video encoder 10002 according to the embodiments encodesthe point cloud video data. According to embodiments, the point cloudvideo encoder 10002 may be referred to as a point cloud encoder, a pointcloud data encoder, an encoder, or the like. The point cloud compressioncoding (encoding) according to the embodiments is not limited to theabove-described embodiment. The point cloud video encoder may output abitstream containing the encoded point cloud video data. The bitstreammay not only include encoded point cloud video data, but also includesignaling information related to encoding of the point cloud video data.

The encoder according to the embodiments may support both thegeometry-based point cloud compression (G-PCC) encoding scheme and/orthe video-based point cloud compression (V-PCC) encoding scheme. Inaddition, the encoder may encode a point cloud (referring to eitherpoint cloud data or points) and/or signaling data related to the pointcloud. The specific operation of encoding according to embodiments willbe described below.

As used herein, the term V-PCC may stand for Video-based Point CloudCompression (V-PCC). The term V-PCC may be the same as Visual VolumetricVideo-based Coding (V3C). These terms may be complementarily used.

The file/segment encapsulation module 10003 according to the embodimentsencapsulates the point cloud data in the form of a file and/or segmentform. The point cloud data transmission method/device according to theembodiments may transmit the point cloud data in a file and/or segmentform.

The transmitter (or communication module) 10004 according to theembodiments transmits the encoded point cloud video data in the form ofa bitstream. According to embodiments, the file or segment may betransmitted to a reception device over a network, or stored in a digitalstorage medium (e.g., USB, SD, CD, DVD, Blu-ray, HDD, SSD, etc.). Thetransmitter according to the embodiments is capable of wired/wirelesscommunication with the reception device (or the receiver) over a networkof 4G, 5G, 6G, etc. In addition, the transmitter may perform necessarydata processing operation according to the network system (e.g., a 4G,5G or 6G communication network system). The transmission device maytransmit the encapsulated data in an on-demand manner.

A point cloud data reception device 10005 according to the embodimentsmay include a receiver 10006, a file/segment decapsulation module 10007,a point cloud video decoder 10008, and/or a renderer 10009. According toembodiments, the reception device may include a device robot, a vehicle,AR/VR/XR devices, a portable device, a home appliance, an Internet ofThing (IoT) device, and an AI device/server which are configured toperform communication with a base station and/or other wireless devicesusing a radio access technology (e.g., 5G New RAT (NR), Long TermEvolution (LTE)).

The receiver 10006 according to the embodiments receives a bitstreamcontaining point cloud video data. According to embodiments, thereceiver 10006 may transmit feedback information to the point cloud datatransmission device 10000.

The file/segment decapsulation module 10007 decapsulates a file and/or asegment containing point cloud data. The decapsulation module accordingto the embodiments may perform a reverse process of the encapsulationprocess according to the embodiments.

The point cloud video decoder 10007 decodes the received point cloudvideo data. The decoder according to the embodiments may perform areverse process of encoding according to the embodiments.

The renderer 10009 renders the decoded point cloud video data. Accordingto embodiments, the renderer 10009 may transmit the feedback informationobtained at the reception side to the point cloud video decoder 10008.The point cloud video data according to the embodiments may carryfeedback information to the receiver. According to embodiments, thefeedback information received by the point cloud transmission device maybe provided to the point cloud video encoder.

The arrows indicated by dotted lines in the drawing represent atransmission path of feedback information acquired by the receptiondevice 10005. The feedback information is information for reflectinginteractivity with a user who consumes point cloud content, and includesuser information (e.g., head orientation information), viewportinformation, and the like). In particular, when the point cloud contentis content for a service (e.g., self-driving service, etc.) thatrequires interaction with a user, the feedback information may beprovided to the content transmitting side (e.g., the transmission device10000) and/or the service provider. According to embodiments, thefeedback information may be used in the reception device 10005 as wellas the transmission device 10000, and may not be provided.

The head orientation information according to embodiments is informationabout a user's head position, orientation, angle, motion, and the like.The reception device 10005 according to the embodiments may calculateviewport information based on the head orientation information. Theviewport information may be information about a region of the pointcloud video that the user is viewing. A viewpoint is a point where auser is viewing a point cloud video, and may refer to a center point ofthe viewport region. That is, the viewport is a region centered on theviewpoint, and the size and shape of the region may be determined by afield of view (FOV). Accordingly, the reception device 10005 may extractthe viewport information based on a vertical or horizontal FOV supportedby the device in addition to the head orientation information. Inaddition, the reception device 10005 performs gaze analysis to check howthe user consumes a point cloud, a region that the user gazes at in thepoint cloud video, a gaze time, and the like. According to embodiments,the reception device 10005 may transmit feedback information includingthe result of the gaze analysis to the transmission device 10000. Thefeedback information according to the embodiments may be acquired in therendering and/or display process. The feedback information according tothe embodiments may be secured by one or more sensors included in thereception device 10005. In addition, according to embodiments, thefeedback information may be secured by the renderer 10009 or a separateexternal element (or device, component, etc.). The dotted lines in FIG.1 represent a process of transmitting the feedback information securedby the renderer 10009. The point cloud content providing system mayprocess (encode/decode) point cloud data based on the feedbackinformation. Accordingly, the point cloud video data decoder 10008 mayperform a decoding operation based on the feedback information. Thereception device 10005 may transmit the feedback information to thetransmission device. The transmission device (or the point cloud videodata encoder 10002) may perform an encoding operation based on thefeedback information. Accordingly, the point cloud content providingsystem may efficiently process necessary data (e.g., point cloud datacorresponding to the user's head position) based on the feedbackinformation rather than processing (encoding/decoding) all point clouddata, and provide point cloud content to the user.

According to embodiments, the transmission device 10000 may be called anencoder, a transmission device, a transmitter, or the like, and thereception device 10004 may be called a decoder, a reception device, areceiver, or the like.

The point cloud data processed in the point cloud content providingsystem of FIG. 1 according to embodiments (through a series of processesof acquisition/encoding/transmission/decoding/rendering) may be referredto as point cloud content data or point cloud video data. According toembodiments, the point cloud content data may be used as a conceptcovering metadata or signaling information related to point cloud data.

The elements of the point cloud content providing system illustrated inFIG. 1 may be implemented by hardware, software, a processor, and/orcombinations thereof.

Embodiments may provide a method of providing point cloud content toprovide a user with various services such as virtual reality (VR),augmented reality (AR), mixed reality (MR), and self-driving.

In order to provide a point cloud content service, a point cloud videomay be acquired first. The acquired point cloud video may be transmittedthrough a series of processes, and the reception side may process thereceived data back into the original point cloud video and render theprocessed point cloud video. Thereby, the point cloud video may beprovided to the user. Embodiments provide a method of effectivelyperforming this series of processes.

The entire processes for providing a point cloud content service (thepoint cloud data transmission method and/or point cloud data receptionmethod) may include an acquisition process, an encoding process, atransmission process, a decoding process, a rendering process, and/or afeedback process.

According to embodiments, the process of providing point cloud content(or point cloud data) may be referred to as a point cloud compressionprocess. According to embodiments, the point cloud compression processmay represent a geometry-based point cloud compression process.

Each element of the point cloud data transmission device and the pointcloud data reception device according to the embodiments may behardware, software, a processor, and/or a combination thereof.

In order to provide a point cloud content service, a point cloud videomay be acquired. The acquired point cloud video is transmitted through aseries of processes, and the reception side may process the receiveddata back into the original point cloud video and render the processedpoint cloud video. Thereby, the point cloud video may be provided to theuser. Embodiments provide a method of effectively performing this seriesof processes.

The entire processes for providing a point cloud content service mayinclude an acquisition process, an encoding process, a transmissionprocess, a decoding process, a rendering process, and/or a feedbackprocess.

The point cloud compression system may include a transmission device anda reception device. The transmission device may output a bitstream byencoding a point cloud video, and deliver the same to the receptiondevice through a digital storage medium or a network in the form of afile or a stream (streaming segment). The digital storage medium mayinclude various storage media such as a USB, SD, CD, DVD, Blu-ray, HDD,and SSD.

The transmission device may include a point cloud video acquirer, apoint cloud video encoder, a file/segment encapsulator, and atransmitter. The reception device may include a receiver, a file/segmentdecapsulator, a point cloud video decoder, and a renderer. The encodermay be referred to as a point cloud video/picture/picture/frame encoder,and the decoder may be referred to as a point cloudvideo/picture/picture/frame decoding device. The transmitter may beincluded in the point cloud video encoder. The receiver may be includedin the point cloud video decoder. The renderer may include a display.The renderer and/or the display may be configured as separate devices orexternal components. The transmission device and the reception devicemay further include a separate internal or externalmodule/unit/component for the feedback process.

According to embodiments, the operation of the reception device may bethe reverse process of the operation of the transmission device.

The point cloud video acquirer may perform the process of acquiringpoint cloud video through a process of capturing, composing, orgenerating point cloud video. In the acquisition process, data of 3Dpositions (x, y, z)/attributes (color, reflectance, transparency, etc.)of multiple points, for example, a polygon file format (PLY) (or theStanford Triangle format) file may be generated. For a video havingmultiple frames, one or more files may be acquired. During the captureprocess, point cloud related metadata (e.g., capture related metadata)may be generated.

A point cloud data transmission device according to embodiments mayinclude an encoder configured to encode point cloud data, and atransmitter configured to transmit the point cloud data. The data may betransmitted in the form of a bitstream containing a point cloud.

A point cloud data reception device according to embodiments may includea receiver configured to receive point cloud data, a decoder configuredto decode the point cloud data, and a renderer configured to render thepoint cloud data.

The method/device according to the embodiments represents the pointcloud data transmission device and/or the point cloud data receptiondevice.

FIG. 2 illustrates capture of point cloud data according to embodiments.

Point cloud data according to embodiments may be acquired by a camera orthe like. A capturing technique according to embodiments may include,for example, inward-facing and/or outward-facing.

In the inward-facing according to the embodiments, one or more camerasinwardly facing an object of point cloud data may photograph the objectfrom the outside of the object.

In the outward-facing according to the embodiments, one or more camerasoutwardly facing an object of point cloud data may photograph theobject. For example, according to embodiments, there may be fourcameras.

The point cloud data or the point cloud content according to theembodiments may be a video or a still image of an object/environmentrepresented in various types of 3D spaces. According to embodiments, thepoint cloud content may include video/audio/an image of an object.

For capture of point cloud content, a combination of camera equipment (acombination of an infrared pattern projector and an infrared camera)capable of acquiring depth and RGB cameras capable of extracting colorinformation corresponding to the depth information may be configured.Alternatively, the depth information may be extracted through LiDAR,which uses a radar system that measures the location coordinates of areflector by emitting a laser pulse and measuring the return time. Ashape of the geometry consisting of points in a 3D space may beextracted from the depth information, and an attribute representing thecolor/reflectance of each point may be extracted from the RGBinformation. The point cloud content may include information about thepositions (x, y, z) and color (YCbCr or RGB) or reflectance (r) of thepoints. For the point cloud content, the outward-facing technique ofcapturing an external environment and the inward-facing technique ofcapturing a central object may be used. In the VR/AR environment, whenan object (e.g., a core object such as a character, a player, a thing,or an actor) is configured into point cloud content that may be viewedby the user in any direction (360 degrees), the configuration of thecapture camera may be based on the inward-facing technique. When thecurrent surrounding environment is configured into point cloud contentin a mode of a vehicle, such as self-driving, the configuration of thecapture camera may be based on the outward-facing technique. Because thepoint cloud content may be captured by multiple cameras, a cameracalibration process may need to be performed before the content iscaptured to configure a global coordinate system for the cameras.

The point cloud content may be a video or still image of anobject/environment presented in various types of 3D spaces.

Additionally, in the point cloud content acquisition method, any pointcloud video may be composed based on the captured point cloud video.Alternatively, when a point cloud video for a computer-generated virtualspace is to be provided, capturing with an actual camera may not beperformed. In this case, the capture process may be replaced simply by aprocess of generating related data.

Post-processing may be needed for the captured point cloud video toimprove the quality of the content. In the video capture process, themaximum/minimum depth may be adjusted within a range provided by thecamera equipment. Even after the adjustment, point data of an unwantedarea may still be present. Accordingly, post-processing of removing theunwanted area (e.g., the background) or recognizing a connected spaceand filling the spatial holes may be performed. In addition, pointclouds extracted from the cameras sharing a spatial coordinate systemmay be integrated into one piece of content through the process oftransforming each point into a global coordinate system based on thecoordinates of the location of each camera acquired through acalibration process. Thereby, one piece of point cloud content having awide range may be generated, or point cloud content with a high densityof points may be acquired.

The point cloud video encoder may encode the input point cloud videointo one or more video streams. One video may include a plurality offrames, each of which may correspond to a still image/picture. In thisspecification, a point cloud video may include a point cloudimage/frame/picture/video/audio. In addition, the term “point cloudvideo” may be used interchangeably with a point cloudimage/frame/picture. The point cloud video encoder may perform avideo-based point cloud compression (V-PCC) procedure. The point cloudvideo encoder may perform a series of procedures such as prediction,transformation, quantization, and entropy coding for compression andencoding efficiency. The encoded data (encoded video/image information)may be output in the form of a bitstream. Based on the V-PCC procedure,the point cloud video encoder may encode point cloud video by dividingthe same into a geometry video, an attribute video, an occupancy mapvideo, and auxiliary information, which will be described later. Thegeometry video may include a geometry image, the attribute video mayinclude an attribute image, and the occupancy map video may include anoccupancy map image. The auxiliary information may include auxiliarypatch information. The attribute video/image may include a texturevideo/image.

The encapsulation processor (file/segment encapsulation module) 1003 mayencapsulate the encoded point cloud video data and/or metadata relatedto the point cloud video in the form of, for example, a file. Here, themetadata related to the point cloud video may be received from themetadata processor. The metadata processor may be included in the pointcloud video encoder or may be configured as a separate component/module.The encapsulation processor may encapsulate the data in a file formatsuch as ISOBMFF or process the same in the form of a DASH segment or thelike. According to an embodiment, the encapsulation processor mayinclude the point cloud video-related metadata in the file format. Thepoint cloud video metadata may be included, for example, in boxes atvarious levels on the ISOBMFF file format or as data in a separate trackwithin the file. According to an embodiment, the encapsulation processormay encapsulate the point cloud video-related metadata into a file. Thetransmission processor may perform processing for transmission on thepoint cloud video data encapsulated according to the file format. Thetransmission processor may be included in the transmitter or may beconfigured as a separate component/module. The transmission processormay process the point cloud video data according to a transmissionprotocol. The processing for transmission may include processing fordelivery over a broadcast network and processing for delivery through abroadband. According to an embodiment, the transmission processor mayreceive point cloud video-related metadata from the metadata processoralong with the point cloud video data, and perform processing of thepoint cloud video data for transmission.

The transmitter 1004 may transmit the encoded video/image information ordata that is output in the form of a bitstream to the receiver of thereception device through a digital storage medium or a network in theform of a file or streaming. The digital storage medium may includevarious storage media such as USB, SD, CD, DVD, Blu-ray, HDD, and SSD.The transmitter may include an element for generating a media file in apredetermined file format, and may include an element for transmissionover a broadcast/communication network. The receiver may extract thebitstream and transmit the extracted bitstream to the decoding device.

The receiver 1003 may receive point cloud video data transmitted by thepoint cloud video transmission device according to the presentdisclosure. Depending on the transmission channel, the receiver mayreceive the point cloud video data over a broadcast network or through abroadband. Alternatively, the point cloud video data may be receivedthrough a digital storage medium.

The reception processor may process the received point cloud video dataaccording to the transmission protocol. The reception processor may beincluded in the receiver or may be configured as a separatecomponent/module. The reception processor may reversely perform theabove-described process of the transmission processor such that theprocessing corresponds to the processing for transmission performed atthe transmission side. The reception processor may deliver the acquiredpoint cloud video data to the decapsulation processor, and the acquiredpoint cloud video-related metadata to the metadata parser. The pointcloud video-related metadata acquired by the reception processor maytake the form of a signaling table.

The decapsulation processor (file/segment decapsulation module) 10007may decapsulate the point cloud video data received in the form of afile from the reception processor. The decapsulation processor maydecapsulate the files according to ISOBMFF or the like, and may acquirea point cloud video bitstream or point cloud video-related metadata (ametadata bitstream). The acquired point cloud video bitstream may bedelivered to the point cloud video decoder, and the acquired point cloudvideo-related metadata (metadata bitstream) may be delivered to themetadata processor. The point cloud video bitstream may include themetadata (metadata bitstream). The metadata processor may be included inthe point cloud video decoder or may be configured as a separatecomponent/module. The point cloud video-related metadata acquired by thedecapsulation processor may take the form of a box or a track in thefile format. The decapsulation processor may receive metadata necessaryfor decapsulation from the metadata processor, when necessary. The pointcloud video-related metadata may be delivered to the point cloud videodecoder and used in a point cloud video decoding procedure, or may betransferred to the renderer and used in a point cloud video renderingprocedure.

The point cloud video decoder may receive the bitstream and decode thevideo/image by performing an operation corresponding to the operation ofthe point cloud video encoder. In this case, the point cloud videodecoder may decode the point cloud video by dividing the same into ageometry video, an attribute video, an occupancy map video, andauxiliary information as described below. The geometry video may includea geometry image, and the attribute video may include an attributeimage. The occupancy map video may include an occupancy map image. Theauxiliary information may include auxiliary patch information. Theattribute video/image may include a texture video/image.

The 3D geometry may be reconstructed based on the decoded geometryimage, the occupancy map, and auxiliary patch information, and then maybe subjected to a smoothing process. A color point cloud image/picturemay be reconstructed by assigning color values to the smoothed 3Dgeometry based on the texture image. The renderer may render thereconstructed geometry and the color point cloud image/picture. Therendered video/image may be displayed through the display. The user mayview all or part of the rendered result through a VR/AR display or atypical display.

The feedback process may include transferring various kinds of feedbackinformation that may be acquired in the rendering/displaying process tothe transmission side or to the decoder of the reception side.Interactivity may be provided through the feedback process in consumingpoint cloud video. According to an embodiment, head orientationinformation, viewport information indicating a region currently viewedby a user, and the like may be delivered to the transmission side in thefeedback process. According to an embodiment, the user may interact withthings implemented in the VR/AR/MR/self-driving environment. In thiscase, information related to the interaction may be delivered to thetransmission side or a service provider during the feedback process.According to an embodiment, the feedback process may be skipped.

The head orientation information may represent information about thelocation, angle and motion of a user's head. On the basis of thisinformation, information about a region of the point cloud videocurrently viewed by the user, that is, viewport information may becalculated.

The viewport information may be information about a region of the pointcloud video currently viewed by the user. Gaze analysis may be performedusing the viewport information to check the way the user consumes thepoint cloud video, a region of the point cloud video at which the usergazes, and how long the user gazes at the region. The gaze analysis maybe performed at the reception side and the result of the analysis may bedelivered to the transmission side on a feedback channel. A device suchas a VR/AR/MR display may extract a viewport region based on thelocation/direction of the user's head, vertical or horizontal FOVsupported by the device, and the like.

According to an embodiment, the aforementioned feedback information maynot only be delivered to the transmission side, but also be consumed atthe reception side. That is, decoding and rendering processes at thereception side may be performed based on the aforementioned feedbackinformation. For example, only the point cloud video for the regioncurrently viewed by the user may be preferentially decoded and renderedbased on the head orientation information and/or the viewportinformation.

Here, the viewport or viewport region may represent a region of thepoint cloud video currently viewed by the user. A viewpoint is a pointwhich is viewed by the user in the point cloud video and may represent acenter point of the viewport region. That is, a viewport is a regionaround a viewpoint, and the size and form of the region may bedetermined by the field of view (FOV).

The present disclosure relates to point cloud video compression asdescribed above. For example, the methods/embodiments disclosed in thepresent disclosure may be applied to the point cloud compression orpoint cloud coding (PCC) standard of the moving picture experts group(MPEG) or the next generation video/image coding standard.

As used herein, a picture/frame may generally represent a unitrepresenting one image in a specific time interval.

A pixel or a pel may be the smallest unit constituting one picture (orimage). Also, “sample” may be used as a term corresponding to a pixel. Asample may generally represent a pixel or a pixel value. It mayrepresent only a pixel/pixel value of a luma component, only apixel/pixel value of a chroma component, or only a pixel/pixel value ofa depth component.

A unit may represent a basic unit of image processing. The unit mayinclude at least one of a specific region of the picture and informationrelated to the region. The unit may be used interchangeably with termsuch as block or area in some cases. In a general case, an M×N block mayinclude samples (or a sample array) or a set (or array) of transformcoefficients configured in M columns and N rows.

FIG. 3 illustrates an example of a point cloud, a geometry image, and atexture image according to embodiments.

A point cloud according to the embodiments may be input to the V-PCCencoding process of FIG. 4, which will be described later, to generate ageometric image and a texture image. According to embodiments, a pointcloud may have the same meaning as point cloud data.

As shown in the figure, the left part shows a point cloud, in which anobject is positioned in a 3D space and may be represented by a boundingbox or the like. The middle part shows the geometry, and the right partshows a texture image (non-padded image).

Video-based point cloud compression (V-PCC) according to embodiments mayprovide a method of compressing 3D point cloud data based on a 2D videocodec such as HEVC or VVC. Data and information that may be generated inthe V-PCC compression process are as follows:

Occupancy map: this is a binary map indicating whether there is data ata corresponding position in a 2D plane, using a value of 0 or 1 individing the points constituting a point cloud into patches and mappingthe same to the 2D plane. The occupancy map may represent a 2D arraycorresponding to ATLAS, and the values of the occupancy map may indicatewhether each sample position in the atlas corresponds to a 3D point. Anatlas is a collection of 2D bounding boxes positioned in a rectangularframe that correspond to a 3D bounding box in a 3D space in whichvolumetric data is rendered and information related thereto.

The atlas bitstream is a bitstream for one or more atlas framesconstituting an atlas and related data.

The atlas frame is a 2D rectangular array of atlas samples onto whichpatches are projected.

An atlas sample is a position of a rectangular frame onto which patchesassociated with the atlas are projected.

An atlas frame may be partitioned into tiles. A tile is a unit in whicha 2D frame is partitioned. That is, a tile is a unit for partitioningsignaling information of point cloud data called an atlas.

Patch: A set of points constituting a point cloud, which indicates thatpoints belonging to the same patch are adjacent to each other in 3Dspace and are mapped in the same direction among 6-face bounding boxplanes in the process of mapping to a 2D image.

A patch is a unit in which a tile partitioned. The patch is signalinginformation on the configuration of point cloud data.

The reception device according to the embodiments may restore attributevideo data, geometry video data, and occupancy video data, which areactual video data having the same presentation time, based on an atlas(tile, patch).

Geometry image: this is an image in the form of a depth map thatpresents position information (geometry) about each point constituting apoint cloud on a patch-by-patch basis. The geometry image may becomposed of pixel values of one channel. Geometry represents a set ofcoordinates associated with a point cloud frame.

Texture image: this is an image representing the color information abouteach point constituting a point cloud on a patch-by-patch basis. Atexture image may be composed of pixel values of a plurality of channels(e.g., three channels of R, G, and B). The texture is included in anattribute. According to embodiments, a texture and/or attribute may beinterpreted as the same object and/or having an inclusive relationship.

Auxiliary patch info: this indicates metadata needed to reconstruct apoint cloud with individual patches. Auxiliary patch info may includeinformation about the position, size, and the like of a patch in a 2D/3Dspace.

Point cloud data according to the embodiments, for example, V-PCCcomponents may include an atlas, an occupancy map, geometry, andattributes.

Atlas represents a set of 2D bounding boxes. It may be patches, forexample, patches projected onto a rectangular frame. Atlas maycorrespond to a 3D bounding box in a 3D space, and may represent asubset of a point cloud.

An attribute may represent a scalar or vector associated with each pointin the point cloud. For example, the attributes may include color,reflectance, surface normal, time stamps, material ID.

The point cloud data according to the embodiments represents PCC dataaccording to video-based point cloud compression (V-PCC) scheme. Thepoint cloud data may include a plurality of components. For example, itmay include an occupancy map, a patch, geometry and/or texture.

FIG. 4 illustrates a V-PCC encoding process according to embodiments.

The figure illustrates a V-PCC encoding process for generating andcompressing an occupancy map, a geometry image, a texture image, andauxiliary patch information. The V-PCC encoding process of FIG. 4 may beprocessed by the point cloud video encoder 10002 of FIG. 1. Each elementof FIG. 4 may be performed by software, hardware, processor and/or acombination thereof.

The patch generation or patch generator 40000 receives a point cloudframe (which may be in the form of a bitstream containing point clouddata). The patch generator 40000 generates a patch from the point clouddata. In addition, patch information including information about patchgeneration is generated.

The patch packing or patch packer 40001 packs patches for point clouddata. For example, one or more patches may be packed. In addition, thepatch packer generates an occupancy map containing information aboutpatch packing.

The geometry image generation or geometry image generator 40002generates a geometry image based on the point cloud data, patches,and/or packed patches. The geometry image refers to data containinggeometry related to the point cloud data.

The texture image generation or texture image generator 40003 generatesa texture image based on the point cloud data, patches, and/or packedpatches. In addition, the texture image may be generated further basedon smoothed geometry generated by smoothing processing of smoothingbased on the patch information.

The smoothing or smoother 40004 may mitigate or eliminate errorscontained in the image data. For example, based on the patchedreconstructed geometry image, portions that may cause errors betweendata may be smoothly filtered out to generate smoothed geometry.

The auxiliary patch info compression or auxiliary patch info compressor40005, auxiliary patch information related to the patch informationgenerated in the patch generation is compressed. In addition, thecompressed auxiliary patch information may be transmitted to themultiplexer. The auxiliary patch information may be used in the geometryimage generation 40002.

The image padding or image padder 40006, 40007 may pad the geometryimage and the texture image, respectively. The padding data may bepadded to the geometry image and the texture image.

The group dilation or group dilator 40008 may add data to the textureimage in a similar manner to image padding. The added data may beinserted into the texture image.

The video compression or video compressor 40009, 40010, 40011 maycompress the padded geometry image, the padded texture image, and/or theoccupancy map, respectively. The compression may encode geometryinformation, texture information, occupancy information, and the like.

The entropy compression or entropy compressor 40012 may compress (e.g.,encode) the occupancy map based on an entropy scheme.

According to embodiments, the entropy compression and/or videocompression may be performed, respectively depending on whether thepoint cloud data is lossless and/or lossy.

The multiplexer 40013 multiplexes the compressed geometry image, thecompressed texture image, and the compressed occupancy map into abitstream.

The specific operations in the respective processes of FIG. 4 aredescribed below.

Patch Generation 40000

The patch generation process refers to a process of dividing a pointcloud into patches, which are mapping units, in order to map the pointcloud to the 2D image. The patch generation process may be divided intothree steps: normal value calculation, segmentation, and patchsegmentation.

The normal value calculation process will be described in detail withreference to FIG. 5.

FIG. 5 illustrates an example of a tangent plane and a normal vector ofa surface according to embodiments.

The surface of FIG. 5 is used in the patch generation process 40000 ofthe V-PCC encoding process of FIG. 4 as follows.

Normal calculation related to patch generation:

Each point of a point cloud has its own direction, which is representedby a 3D vector called a normal vector. Using the neighbors of each pointobtained using a K-D tree or the like, a tangent plane and a normalvector of each point constituting the surface of the point cloud asshown in the figure may be obtained. The search range applied to theprocess of searching for neighbors may be defined by the user.

The tangent plane refers to a plane that passes through a point on thesurface and completely includes a tangent line to the curve on thesurface.

FIG. 6 illustrates an exemplary bounding box of a point cloud accordingto embodiments.

A method/device according to embodiments, for example, patch generation,may employ a bounding box in generating a patch from point cloud data.

The bounding box according to the embodiments refers to a box of a unitfor dividing point cloud data based on a hexahedron in a 3D space.

The bounding box may be used in the process of projecting a targetobject of the point cloud data onto a plane of each planar face of ahexahedron in a 3D space. The bounding box may be generated andprocessed by the point cloud video acquirer 10000 and the point cloudvideo encoder 10002 of FIG. 1. Further, based on the bounding box, thepatch generation 40000, patch packing 40001, geometry image generation40002, and texture image generation 40003 of the V-PCC encoding processof FIG. 2 may be performed.

Segmentation Related to Patch Generation

Segmentation is divided into two processes: initial segmentation andrefine segmentation.

The point cloud encoder 10002 according to the embodiments projects apoint onto one face of a bounding box. Specifically, each pointconstituting a point cloud is projected onto one of the six faces of abounding box surrounding the point cloud as shown in the figure. Initialsegmentation is a process of determining one of the planar faces of thebounding box onto which each point is to be projected.

{right arrow over (n)}_(Pidx), which is a normal value corresponding toeach of the six planar faces, is defined as follows:

(1.0, 0.0, 0.0), (0.0, 1.0, 0.0), (0.0, 0.0, 1.0), (−1.0, 0.0, 0.0),(0.0, −1.0, 0.0), (0.0, 0.0, −1.0).

As shown in the equation below, a face that yields the maximum value ofdot product of the normal vector {right arrow over (n)}_(pi) of eachpoint, which is obtained in the normal value calculation process, and{right arrow over (n)}_(pidx) is determined as a projection plane of thecorresponding point. That is, a plane whose normal vector is mostsimilar to the direction of the normal vector of a point is determinedas the projection plane of the point.

$\max\limits_{p_{idx}}\left\{ {{\overset{\rightarrow}{n}}_{p_{i}} \cdot {\overset{\rightarrow}{n}}_{p_{idx}}} \right\}$

The determined plane may be identified by one cluster index, which isone of 0 to 5.

Refine segmentation is a process of enhancing the projection plane ofeach point constituting the point cloud determined in the initialsegmentation process in consideration of the projection planes ofneighboring points. In this process, a score normal, which representsthe degree of similarity between the normal vector of each point and thenormal of each planar face of the bounding box which are considered indetermining the projection plane in the initial segmentation process,and score smooth, which indicates the degree of similarity between theprojection plane of the current point and the projection planes ofneighboring points, may be considered together.

Score smooth may be considered by assigning a weight to the scorenormal. In this case, the weight value may be defined by the user. Therefine segmentation may be performed repeatedly, and the number ofrepetitions may also be defined by the user.

Patch Segmentation Related to Patch Generation

Patch segmentation is a process of dividing the entire point cloud intopatches, which are sets of neighboring points, based on the projectionplane information about each point constituting the point cloud obtainedin the initial/refine segmentation process. The patch segmentation mayinclude the following steps:

1) Calculate neighboring points of each point constituting the pointcloud, using the K-D tree or the like. The maximum number of neighborsmay be defined by the user;

2) When the neighboring points are projected onto the same plane as thecurrent point (when they have the same cluster index), extract thecurrent point and the neighboring points as one patch;

3) Calculate geometry values of the extracted patch. The details aredescribed below; and

4) Repeat operations 2) to 4) until there is no unextracted point.

The occupancy map, geometry image and texture image for each patch aswell as the size of each patch are determined through the patchsegmentation process.

FIG. 7 illustrates an example of determination of individual patchpositions on an occupancy map according to embodiments.

The point cloud encoder 10002 according to the embodiments may performpatch packing and generate an occupancy map.

Patch Packing & Occupancy Map Generation (40001)

This is a process of determining the positions of individual patches ina 2D image to map the segmented patches to the 2D image. The occupancymap, which is a kind of 2D image, is a binary map that indicates whetherthere is data at a corresponding position, using a value of 0 or 1. Theoccupancy map is composed of blocks and the resolution thereof may bedetermined by the size of the block. For example, when the block is 1*1block, a pixel-level resolution is obtained. The occupancy packing blocksize may be determined by the user.

The process of determining the positions of individual patches on theoccupancy map may be configured as follows:

1) Set all positions on the occupancy map to 0;

2) Place a patch at a point (u, v) having a horizontal coordinate withinthe range of (0, occupancySizeU-patch.sizeU0) and a vertical coordinatewithin the range of (0, occupancySizeV-patch.sizeV0) in the occupancymap plane;

3) Set a point (x, y) having a horizontal coordinate within the range of(0, patch.sizeU0) and a vertical coordinate within the range of (0,patch.sizeV0) in the patch plane as a current point;

4) Change the position of point (x, y) in raster order and repeatoperations 3) and 4) if the value of coordinate (x, y) on the patchoccupancy map is 1 (there is data at the point in the patch) and thevalue of coordinate (u+x, v+y) on the global occupancy map is 1 (theoccupancy map is filled with the previous patch). Otherwise, proceed tooperation 6);

5) Change the position of (u, v) in raster order and repeat operations3) to 5);

6) Determine (u, v) as the position of the patch and copy the occupancymap data about the patch onto the corresponding portion on the globaloccupancy map; and

7) Repeat operations 2) to 7) for the next patch.

occupancySizeU: indicates the width of the occupancy map. The unitthereof is occupancy packing block size.

occupancySizeV: indicates the height of the occupancy map. The unitthereof is occupancy packing block size.

patch.sizeU0: indicates the width of the occupancy map. The unit thereofis occupancy packing block size.

patch.sizeV0: indicates the height of the occupancy map. The unitthereof is occupancy packing block size.

For example, as shown in FIG. 7, there is a box corresponding to a patchhaving a patch size in a box corresponding to an occupancy packing sizeblock, and a point (x, y) may be located in the box.

FIG. 8 shows an exemplary relationship among normal, tangent, andbitangent axes according to embodiments.

The point cloud encoder 10002 according to embodiments may generate ageometry image. The geometry image refers to image data includinggeometry information about a point cloud. The geometry image generationprocess may employ three axes (normal, tangent, and bitangent) of apatch in FIG. 8.

Geometry Image Generation (40002)

In this process, the depth values constituting the geometry images ofindividual patches are determined, and the entire geometry image isgenerated based on the positions of the patches determined in the patchpacking process described above. The process of determining the depthvalues constituting the geometry images of individual patches may beconfigured as follows.

1) Calculate parameters related to the position and size of anindividual patch. The parameters may include the following information.

A normal index indicating the normal axis is obtained in the previouspatch generation process. The tangent axis is an axis coincident withthe horizontal axis u of the patch image among the axes perpendicular tothe normal axis, and the bitangent axis is an axis coincident with thevertical axis v of the patch image among the axes perpendicular to thenormal axis. The three axes may be expressed as shown in the figure.

FIG. 9 shows an exemplary configuration of the minimum mode and maximummode of a projection mode according to embodiments.

The point cloud encoder 10002 according to embodiments may performpatch-based projection to generate a geometry image, and the projectionmode according to the embodiments includes a minimum mode and a maximummode.

3D spatial coordinates of a patch may be calculated based on thebounding box of the minimum size surrounding the patch. For example, the3D spatial coordinates may include the minimum tangent value of thepatch (on the patch 3d shift tangent axis) of the patch, the minimumbitangent value of the patch (on the patch 3d shift bitangent axis), andthe minimum normal value of the patch (on the patch 3d shift normalaxis).

2D size of a patch indicates the horizontal and vertical sizes of thepatch when the patch is packed into a 2D image. The horizontal size(patch 2d size u) may be obtained as a difference between the maximumand minimum tangent values of the bounding box, and the vertical size(patch 2d size v) may be obtained as a difference between the maximumand minimum bitangent values of the bounding box.

2) Determine a projection mode of the patch. The projection mode may beeither the min mode or the max mode. The geometry information about thepatch is expressed with a depth value. When each point constituting thepatch is projected in the normal direction of the patch, two layers ofimages, an image constructed with the maximum depth value and an imageconstructed with the minimum depth value, may be generated.

In the min mode, in generating the two layers of images d0 and d1, theminimum depth may be configured for d0, and the maximum depth within thesurface thickness from the minimum depth may be configured for d1, asshown in the figure.

For example, when a point cloud is located in 2D as illustrated in thefigure, there may be a plurality of patches including a plurality ofpoints. As shown in the figure, it is indicated that points marked withthe same style of shadow may belong to the same patch. The figureillustrates the process of projecting a patch of points marked withblanks.

When projecting points marked with blanks to the left/right, the depthmay be incremented by 1 as 0, 1, 2, . . . , 6, 7, 8, 9 with respect tothe left side, and the number for calculating the depths of the pointsmay be marked on the right side.

The same projection mode may be applied to all point clouds or differentprojection modes may be applied to respective frames or patchesaccording to user definition. When different projection modes areapplied to the respective frames or patches, a projection mode that mayenhance compression efficiency or minimize missed points may beadaptively selected.

3) Calculate the depth values of the individual points.

In the min mode, image d0 is constructed with depth0 which is a valueobtained by subtracting the minimum normal value of the patch (on thepatch 3d shift normal axis) calculated in operation 1) from the minimumnormal value of the patch (on the patch 3d shift normal axis) for theminimum normal value of each point. If there is another depth valuewithin the range between depth0 and the surface thickness at the sameposition, this value is set to depth1. Otherwise, the value of depth0 isassigned to depth1. Image d1 is constructed with the value of depth1.

For example, a minimum value may be calculated in determining the depthof points of image d0 (4244060099080). In determining the depth ofpoints of image d1, a greater value among two or more points may becalculated. When only one point is present, the value thereof may becalculated (4444666899889). In the process of encoding andreconstructing the points of the patch, some points may be lost (Forexample, in the figure, eight points are lost).

In the max mode, image d0 is constructed with depth0 which is a valueobtained by subtracting the minimum normal value of the patch (on thepatch 3d shift normal axis) calculated in operation 1) from the minimumnormal value of the patch (on the patch 3d shift normal axis) for themaximum normal value of each point. If there is another depth valuewithin the range between depth0 and the surface thickness at the sameposition, this value is set to depth1. Otherwise, the value of depth0 isassigned to depth1. Image d1 is constructed with the value of depth1.

For example, a maximum value may be calculated in determining the depthof points of d0 (4444666899889). In addition, in determining the depthof points of d1, a lower value among two or more points may becalculated. When only one point is present, the value thereof may becalculated (4244560699080). In the process of encoding andreconstructing the points of the patch, some points may be lost (Forexample, in the figure, six points are lost).

The entire geometry image may be generated by placing the geometryimages of the individual patches generated through the above-describedprocesses onto the entire geometry image based on the patch positioninformation determined in the patch packing process.

Layer d1 of the generated entire geometry image may be encoded usingvarious methods. A first method (absolute d1 method) is to encode thedepth values of the previously generated image d1. A second method(differential method) is to encode a difference between the depth valuesof previously generated image d1 and the depth values of image d0.

In the encoding method using the depth values of the two layers, d0 andd1 as described above, if there is another point between the two depths,the geometry information about the point is lost in the encodingprocess, and therefore an enhanced-delta-depth (EDD) code may be usedfor lossless coding.

Hereinafter, the EDD code will be described in detail with reference toFIG. 10.

FIG. 10 illustrates an exemplary EDD code according to embodiments.

In some/all processes of the point cloud encoder 10002 and/or V-PCCencoding (e.g., video compression 40009), the geometry information aboutpoints may be encoded based on the EOD code.

As shown in the figure, the EDD code is used for binary encoding of thepositions of all points within the range of surface thickness includingd1. For example, in the figure, the points included in the second leftcolumn may be represented by an EDD code of 0b1001 (=9) because thepoints are present at the first and fourth positions over DO and thesecond and third positions are empty. When the EDD code is encodedtogether with DO and transmitted, a reception terminal may restore thegeometry information about all points without loss.

For example, when there is a point present above a reference point, thevalue is 1. When there is no point, the value is 0. Thus, the code maybe expressed based on 4 bits.

Smoothing (40004)

Smoothing is an operation for eliminating discontinuity that may occuron the patch boundary due to deterioration of the image qualityoccurring during the compression process. Smoothing may be performed bythe point cloud encoder or smoother:

1) Reconstruct the point cloud from the geometry image. This operationmay be the reverse of the geometry image generation described above. Forexample, the reverse process of encoding may be reconstructed;

2) Calculate neighboring points of each point constituting thereconstructed point cloud using the K-D tree or the like;

3) Determine whether each of the points is positioned on the patchboundary. For example, when there is a neighboring point having adifferent projection plane (cluster index) from the current point, itmay be determined that the point is positioned on the patch boundary;

4) If there is a point present on the patch boundary, move the point tothe center of mass of the neighboring points (positioned at the averagex, y, z coordinates of the neighboring points). That is, change thegeometry value. Otherwise, maintain the previous geometry value.

FIG. 11 illustrates an example of recoloring based on color values ofneighboring points according to embodiments.

The point cloud encoder or the texture image generator 40003 accordingto the embodiments may generate a texture image based on recoloring.

Texture Image Generation (40003)

The texture image generation process, which is similar to the geometryimage generation process described above, includes generating textureimages of individual patches and generating an entire texture image byarranging the texture images at determined positions. However, in theoperation of generating texture images of individual patches, an imagewith color values (e.g., R, G, and B values) of the points constitutinga point cloud corresponding to a position is generated in place of thedepth values for geometry generation.

In estimating a color value of each point constituting the point cloud,the geometry previously obtained through the smoothing process may beused. In the smoothed point cloud, the positions of some points may havebeen shifted from the original point cloud, and accordingly a recoloringprocess of finding colors suitable for the changed positions may berequired. Recoloring may be performed using the color values ofneighboring points. For example, as shown in the figure, a new colorvalue may be calculated in consideration of the color value of thenearest neighboring point and the color values of the neighboringpoints.

For example, referring to the figure, in the recoloring, a suitablecolor value for a changed position may be calculated based on theaverage of the attribute information about the closest original pointsto a point and/or the average of the attribute information about theclosest original positions to the point.

Texture images may also be generated in two layers of t0 and t1, likethe geometry images, which are generated in two layers of d0 and d1.

Auxiliary Patch Info Compression (40005)

The point cloud encoder or the auxiliary patch info compressor accordingto the embodiments may compress the auxiliary patch information(auxiliary information about the point cloud).

The auxiliary patch info compressor compresses the auxiliary patchinformation generated in the patch generation, patch packing, andgeometry generation processes described above. The auxiliary patchinformation may include the following parameters:

Index (cluster index) for identifying the projection plane (normalplane);

3D spatial position of a patch, i.e., the minimum tangent value of thepatch (on the patch 3d shift tangent axis), the minimum bitangent valueof the patch (on the patch 3d shift bitangent axis), and the minimumnormal value of the patch (on the patch 3d shift normal axis);

2D spatial position and size of the patch, i.e., the horizontal size(patch 2d size u), the vertical size (patch 2d size v), the minimumhorizontal value (patch 2d shift u), and the minimum vertical value(patch 2d shift u); and

Mapping information about each block and patch, i.e., a candidate index(when patches are disposed in order based on the 2D spatial position andsize information about the patches, multiple patches may be mapped toone block in an overlapping manner. In this case, the mapped patchesconstitute a candidate list, and the candidate index indicates theposition in sequential order of a patch whose data is present in theblock), and a local patch index (which is an index indicating one of thepatches present in the frame). Table X shows a pseudo code representingthe process of matching between blocks and patches based on thecandidate list and the local patch indexes.

The maximum number of candidate lists may be defined by a user.

TABLE 1-1 Pseudo code for mapping a block to a patch for( i = 0; i <BlockCount; i++ ) { if( candidatePatches[ i ].size( ) = = 1 ) {blockToPatch[ i ] = candidatePatches[ i ][ 0 ] } else { candidate_indexif( candidate_index = = max_candidate_count ) { blockToPatch[ i ] =local_patch_index } else { blockToPatch[ i ] = candidatePatches[ i ][candidate_index ] } } }

FIG. 12 illustrates push-pull background filling according toembodiments.

Image Padding and Group Dilation (40006, 40007, 40008)

The image padder according to the embodiments may fill the space exceptthe patch area with meaningless supplemental data based on the push-pullbackground filling technique.

Image padding is a process of filling the space other than the patchregion with meaningless data to improve compression efficiency. Forimage padding, pixel values in columns or rows close to a boundary inthe patch may be copied to fill the empty space. Alternatively, as shownin the figure, a push-pull background filling method may be used.According to this method, the empty space is filled with pixel valuesfrom a low resolution image in the process of gradually reducing theresolution of a non-padded image and increasing the resolution again.

Group dilation is a process of filling the empty spaces of a geometryimage and a texture image configured in two layers, d0/d1 and t0/t1,respectively. In this process, the empty spaces of the two layerscalculated through image padding are filled with the average of thevalues for the same position.

FIG. 13 shows an exemplary possible traversal order for a 4*4 blockaccording to embodiments.

Occupancy Map Compression (40012, 40011)

The occupancy map compressor according to the embodiments may compressthe previously generated occupancy map. Specifically, two methods,namely video compression for lossy compression and entropy compressionfor lossless compression, may be used. Video compression is describedbelow.

The entropy compression may be performed through the followingoperations.

1) If a block constituting an occupancy map is fully occupied, encode 1and repeat the same operation for the next block of the occupancy map.Otherwise, encode 0 and perform operations 2) to 5).

2) Determine the best traversal order to perform run-length coding onthe occupied pixels of the block. The figure shows four possibletraversal orders for a 4*4 block.

FIG. 14 illustrates an exemplary best traversal order according toembodiments.

As described above, the entropy compressor according to the embodimentsmay code (encode) a block based on the traversal order scheme asdescribed above.

For example, the best traversal order with the minimum number of runs isselected from among the possible traversal orders and the index thereofis encoded. The figure illustrates a case where the third traversalorder in FIG. 13 is selected. In the illustrated case, the number ofruns may be minimized to 2, and therefore the third traversal order maybe selected as the best traversal order.

3) Encode the number of runs. In the example of FIG. 14, there are tworuns, and therefore 2 is encoded.

4) Encode the occupancy of the first run. In the example of FIG. 14, 0is encoded because the first run corresponds to unoccupied pixels.

5) Encode lengths of the individual runs (as many as the number ofruns). In the example of FIG. 14, the lengths of the first run and thesecond run, 6 and 10, are sequentially encoded.

Video Compression (40009, 40010, 40011)

The video compressor according to the embodiments encodes a sequence ofa geometry image, a texture image, an occupancy map image, and the likegenerated in the above-described operations, using a 2D video codec suchas HEVC or VVC.

FIG. 15 illustrates an exemplary 2D video/image encoder according toembodiments.

The figure, which represents an embodiment to which the videocompression or video compressor 40009, 40010, and 40011 described aboveis applied, is a schematic block diagram of a 2D video/image encoder15000 configured to encode a video/image signal. The 2D video/imageencoder 15000 may be included in the point cloud video encoder describedabove or may be configured as an internal/external component. Eachcomponent of FIG. 15 may correspond to software, hardware, processorand/or a combination thereof.

Here, the input image may include the geometry image, the texture image(attribute(s) image), and the occupancy map image described above. Theoutput bitstream (i.e., the point cloud video/image bitstream) of thepoint cloud video encoder may include output bitstreams for therespective input images (i.e., the geometry image, the texture image(attribute(s) image), the occupancy map image, etc.).

An inter-predictor 15090 and an intra-predictor 15100 may becollectively called a predictor. That is, the predictor may include theinter-predictor 15090 and the intra-predictor 15100. A transformer15030, a quantizer 15040, an inverse quantizer 15050, and an inversetransformer 15060 may be included in the residual processor. Theresidual processor may further include a subtractor 15020. According toan embodiment, the image splitter 15010, the subtractor 15020, thetransformer 15030, the quantizer 15040, the inverse quantizer 15050, theinverse transformer 15060, the adder 155, the filter 15070, theinter-predictor 15090, the intra-predictor 15100, and the entropyencoder 15110 described above may be configured by one hardwarecomponent (e.g., an encoder or a processor). In addition, the memory15080 may include a decoded picture buffer (DPB) and may be configuredby a digital storage medium.

The image splitter 15010 may spit an image (or a picture or a frame)input to the encoder 15000 into one or more processing units. Forexample, the processing unit may be called a coding unit (CU). In thiscase, the CU may be recursively split from a coding tree unit (CTU) or alargest coding unit (LCU) according to a quad-tree binary-tree (QTBT)structure. For example, one CU may be split into a plurality of CUs of alower depth based on a quad-tree structure and/or a binary-treestructure. In this case, for example, the quad-tree structure may beapplied first and the binary-tree structure may be applied later.Alternatively, the binary-tree structure may be applied first. Thecoding procedure according to the present disclosure may be performedbased on a final CU that is not split anymore. In this case, the LCU maybe used as the final CU based on coding efficiency according tocharacteristics of the image. When necessary, a CU may be recursivelysplit into CUs of a lower depth, and a CU of the optimum size may beused as the final CU. Here, the coding procedure may include prediction,transformation, and reconstruction, which will be described later. Asanother example, the processing unit may further include a predictionunit (PU) or a transform unit (TU). In this case, the PU and the TU maybe split or partitioned from the aforementioned final CU. The PU may bea unit of sample prediction, and the TU may be a unit for deriving atransform coefficient and/or a unit for deriving a residual signal fromthe transform coefficient.

The term “unit” may be used interchangeably with terms such as block orarea. In a general case, an M×N block may represent a set of samples ortransform coefficients configured in M columns and N rows. A sample maygenerally represent a pixel or a value of a pixel, and may indicate onlya pixel/pixel value of a luma component, or only a pixel/pixel value ofa chroma component. “Sample” may be used as a term corresponding to apixel or a pel in one picture (or image).

The encoder 15000 may generate a residual signal (residual block orresidual sample array) by subtracting a prediction signal (predictedblock or predicted sample array) output from the inter-predictor 15090or the intra-predictor 15100 from an input image signal (original blockor original sample array), and the generated residual signal istransmitted to the transformer 15030. In this case, as shown in thefigure, the unit that subtracts the prediction signal (predicted blockor predicted sample array) from the input image signal (original blockor original sample array) in the encoder 15000 may be called asubtractor 15020. The predictor may perform prediction for a processingtarget block (hereinafter referred to as a current block) and generate apredicted block including prediction samples for the current block. Thepredictor may determine whether intra-prediction or inter-prediction isapplied on a current block or CU basis. As will be described later inthe description of each prediction mode, the predictor may generatevarious kinds of information about prediction, such as prediction modeinformation, and deliver the generated information to the entropyencoder 15110. The information about the prediction may be encoded andoutput in the form of a bitstream by the entropy encoder 15110.

The intra-predictor 15100 may predict the current block with referenceto the samples in the current picture. The samples may be positioned inthe neighbor of or away from the current block depending on theprediction mode. In intra-prediction, the prediction modes may include aplurality of non-directional modes and a plurality of directional modes.The non-directional modes may include, for example, a DC mode and aplanar mode. The directional modes may include, for example, 33directional prediction modes or 65 directional prediction modesaccording to fineness of the prediction directions. However, this ismerely an example, and more or fewer directional prediction modes may beused depending on the setting. The intra-predictor 15100 may determine aprediction mode to be applied to the current block, based on theprediction mode applied to the neighboring block.

The inter-predictor 15090 may derive a predicted block for the currentblock based on a reference block (reference sample array) specified by amotion vector on the reference picture. In this case, in order to reducethe amount of motion information transmitted in the inter-predictionmode, the motion information may be predicted on a per block, subblock,or sample basis based on the correlation in motion information betweenthe neighboring blocks and the current block. The motion information mayinclude a motion vector and a reference picture index. The motioninformation may further include information about an inter-predictiondirection (L0 prediction, L1 prediction, Bi prediction, etc.). In thecase of inter-prediction, the neighboring blocks may include a spatialneighboring block, which is present in the current picture, and atemporal neighboring block, which is present in the reference picture.The reference picture including the reference block may be the same asor different from the reference picture including the temporalneighboring block. The temporal neighboring block may be referred to asa collocated reference block or a collocated CU (colCU), and thereference picture including the temporal neighboring block may bereferred to as a collocated picture (colPic). For example, theinter-predictor 15090 may configure a motion information candidate listbased on the neighboring blocks and generate information indicating acandidate to be used to derive a motion vector and/or a referencepicture index of the current block. Inter-prediction may be performedbased on various prediction modes. For example, in a skip mode and amerge mode, the inter-predictor 15090 may use motion information about aneighboring block as motion information about the current block. In theskip mode, unlike the merge mode, the residual signal may not betransmitted. In a motion vector prediction (MVP) mode, the motion vectorof a neighboring block may be used as a motion vector predictor and themotion vector difference may be signaled to indicate the motion vectorof the current block.

The prediction signal generated by the inter-predictor 15090 or theintra-predictor 15100 may be used to generate a reconstruction signal orto generate a residual signal.

The transformer 15030 may generate transform coefficients by applying atransformation technique to the residual signal. For example, thetransformation technique may include at least one of discrete cosinetransform (DCT), discrete sine transform (DST), Karhunen-Loève transform(KLT), graph-based transform (GBT), or conditionally non-lineartransform (CNT). Here, the GBT refers to transformation obtained from agraph depicting the relationship between pixels. The CNT refers totransformation obtained based on a prediction signal generated based onall previously reconstructed pixels. In addition, the transformationoperation may be applied to pixel blocks having the same size of asquare, or may be applied to blocks of a variable size other than thesquare.

The quantizer 15040 may quantize the transform coefficients and transmitthe same to the entropy encoder 15110. The entropy encoder 15110 mayencode the quantized signal (information about the quantized transformcoefficients) and output a bitstream of the encoded signal. Theinformation about the quantized transform coefficients may be referredto as residual information. The quantizer 15040 may rearrange thequantized transform coefficients, which are in a block form, in the formof a one-dimensional vector based on a coefficient scan order, andgenerate information about the quantized transform coefficients based onthe quantized transform coefficients in the form of the one-dimensionalvector. The entropy encoder 15110 may employ various encoding techniquessuch as, for example, exponential Golomb, context-adaptive variablelength coding (CAVLC), and context-adaptive binary arithmetic coding(CABAC). The entropy encoder 15110 may encode information necessary forvideo/image reconstruction (e.g., values of syntax elements) togetherwith or separately from the quantized transform coefficients. Theencoded information (e.g., encoded video/image information) may betransmitted or stored in the form of a bitstream on a networkabstraction layer (NAL) unit basis. The bitstream may be transmittedover a network or may be stored in a digital storage medium. Here, thenetwork may include a broadcast network and/or a communication network,and the digital storage medium may include various storage media such asUSB, SD, CD, DVD, Blu-ray, HDD, and SSD. A transmitter (not shown) totransmit the signal output from the entropy encoder 15110 and/or astorage (not shown) to store the signal may be configured asinternal/external elements of the encoder 15000. Alternatively, thetransmitter may be included in the entropy encoder 15110.

The quantized transform coefficients output from the quantizer 15040 maybe used to generate a prediction signal. For example, inversequantization and inverse transform may be applied to the quantizedtransform coefficients through the inverse quantizer 15050 and theinverse transformer 15060 to reconstruct the residual signal (residualblock or residual samples). The adder 155 may add the reconstructedresidual signal to the prediction signal output from the inter-predictor15090 or the intra-predictor 15100. Thereby, a reconstructed signal(reconstructed picture, reconstructed block, reconstructed sample array)may be generated. When there is no residual signal for a processingtarget block as in the case where the skip mode is applied, thepredicted block may be used as the reconstructed block. The adder 155may be called a reconstructor or a reconstructed block generator. Thegenerated reconstructed signal may be used for intra-prediction of thenext processing target block in the current picture, or may be used forinter-prediction of the next picture through filtering as describedbelow.

The filter 15070 may improve subjective/objective image quality byapplying filtering to the reconstructed signal. For example, the filter15070 may generate a modified reconstructed picture by applying variousfiltering techniques to the reconstructed picture, and the modifiedreconstructed picture may be stored in the memory 15080, specifically,the DPB of the memory 15080. The various filtering techniques mayinclude, for example, deblocking filtering, sample adaptive offset,adaptive loop filtering, and bilateral filtering. As described below inthe description of the filtering techniques, the filter 15070 maygenerate various kinds of information about filtering and deliver thegenerated information to the entropy encoder 15110. The informationabout filtering may be encoded and output in the form of a bitstream bythe entropy encoder 15110.

The modified reconstructed picture transmitted to the memory 15080 maybe used as a reference picture by the inter-predictor 15090. Thus, wheninter-prediction is applied, the encoder may avoid prediction mismatchbetween the encoder 15000 and the decoder and improve encodingefficiency.

The DPB of the memory 15080 may store the modified reconstructed pictureso as to be used as a reference picture by the inter-predictor 15090.The memory 15080 may store the motion information about a block fromwhich the motion information in the current picture is derived (orencoded) and/or the motion information about the blocks in a picturethat has already been reconstructed. The stored motion information maybe delivered to the inter-predictor 15090 so as to be used as motioninformation about a spatial neighboring block or motion informationabout a temporal neighboring block. The memory 15080 may store thereconstructed samples of the reconstructed blocks in the current pictureand deliver the reconstructed samples to the intra-predictor 15100.

At least one of the prediction, transform, and quantization proceduresdescribed above may be skipped. For example, for a block to which thepulse coding mode (PCM) is applied, the prediction, transform, andquantization procedures may be skipped, and the value of the originalsample may be encoded and output in the form of a bitstream.

FIG. 16 illustrates an exemplary V-PCC decoding process according toembodiments.

The V-PCC decoding process or V-PCC decoder may follow the reverseprocess of the V-PCC encoding process (or encoder) of FIG. 4. Eachcomponent in FIG. 16 may correspond to software, hardware, a processor,and/or a combination thereof.

The demultiplexer 16000 demultiplexes the compressed bitstream to outputa compressed texture image, a compressed geometry image, a compressedoccupancy map, and compressed auxiliary patch information.

The video decompression or video decompressor 16001, 16002 decompresses(or decodes) each of the compressed texture image and the compressedgeometry image.

The occupancy map decompression or occupancy map decompressor 16003decompresses the compressed occupancy map.

The auxiliary patch info decompression or auxiliary patch infodecompressor 16004 decompresses auxiliary patch information.

The geometry reconstruction or geometry reconstructor 16005 restores(reconstructs) the geometry information based on the decompressedgeometry image, the decompressed occupancy map, and/or the decompressedauxiliary patch information. For example, the geometry changed in theencoding process may be reconstructed.

The smoothing or smoother 16006 may apply smoothing to the reconstructedgeometry. For example, smoothing filtering may be applied.

The texture reconstruction or texture reconstructor 16007 reconstructsthe texture from the decompressed texture image and/or the smoothedgeometry.

The color smoothing or color smoother 16008 smoothes color values fromthe reconstructed texture. For example, smoothing filtering may beapplied.

As a result, reconstructed point cloud data may be generated.

The figure illustrates a decoding process of the V-PCC forreconstructing a point cloud by decoding the compressed occupancy map,geometry image, texture image, and auxiliary path information. Eachprocess according to the embodiments is operated as follows.

Video Decompression (1600, 16002)

Video decompression is a reverse process of the video compressiondescribed above. In video decompression, a 2D video codec such as HEVCor VVC is used to decode a compressed bitstream containing the geometryimage, texture image, and occupancy map image generated in theabove-described process.

FIG. 17 illustrates an exemplary 2D video/image decoder according toembodiments.

The 2D video/image decoder may follow the reverse process of the 2Dvideo/image encoder of FIG. 15.

The 2D video/image decoder of FIG. 17 is an embodiment of the videodecompression or video decompressor of FIG. 16. FIG. 17 is a schematicblock diagram of a 2D video/image decoder 17000 by which decoding of avideo/image signal is performed. The 2D video/image decoder 17000 may beincluded in the point cloud video decoder of FIG. 1, or may beconfigured as an internal/external component. Each component in FIG. 17may correspond to software, hardware, a processor, and/or a combinationthereof.

Here, the input bitstream may include bitstreams for the geometry image,texture image (attribute(s) image), and occupancy map image describedabove. The reconstructed image (or the output image or the decodedimage) may represent a reconstructed image for the geometry image,texture image (attribute(s) image), and occupancy map image describedabove.

Referring to the figure, an inter-predictor 17070 and an intra-predictor17080 may be collectively referred to as a predictor. That is, thepredictor may include the inter-predictor 17070 and the intra-predictor17080. An inverse quantizer 17020 and an inverse transformer 17030 maybe collectively referred to as a residual processor. That is, theresidual processor may include the inverse quantizer 17020 and theinverse transformer 17030. The entropy decoder 17010, the inversequantizer 17020, the inverse transformer 17030, the adder 17040, thefilter 17050, the inter-predictor 17070, and the intra-predictor 17080described above may be configured by one hardware component (e.g., adecoder or a processor) according to an embodiment. In addition, thememory 170 may include a decoded picture buffer (DPB) or may beconfigured by a digital storage medium.

When a bitstream containing video/image information is input, thedecoder 17000 may reconstruct an image in a process corresponding to theprocess in which the video/image information is processed by the encoderof FIGS. 0.2-1. For example, the decoder 17000 may perform decodingusing a processing unit applied in the encoder. Thus, the processingunit of decoding may be, for example, a CU. The CU may be split from aCTU or an LCU along a quad-tree structure and/or a binary-treestructure. Then, the reconstructed video signal decoded and outputthrough the decoder 17000 may be played through a player.

The decoder 17000 may receive a signal output from the encoder in theform of a bitstream, and the received signal may be decoded through theentropy decoder 17010. For example, the entropy decoder 17010 may parsethe bitstream to derive information (e.g., video/image information)necessary for image reconstruction (or picture reconstruction). Forexample, the entropy decoder 17010 may decode the information in thebitstream based on a coding technique such as exponential Golomb coding,CAVLC, or CABAC, output values of syntax elements required for imagereconstruction, and quantized values of transform coefficients for theresidual. More specifically, in the CABAC entropy decoding, a bincorresponding to each syntax element in the bitstream may be received,and a context model may be determined based on decoding target syntaxelement information and decoding information about neighboring anddecoding target blocks or information about a symbol/bin decoded in aprevious step. Then, the probability of occurrence of a bin may bepredicted according to the determined context model, and arithmeticdecoding of the bin may be performed to generate a symbol correspondingto the value of each syntax element. According to the CABAC entropydecoding, after a context model is determined, the context model may beupdated based on the information about the symbol/bin decoded for thecontext model of the next symbol/bin. Information about the predictionin the information decoded by the entropy decoder 17010 may be providedto the predictors (the inter-predictor 17070 and the intra-predictor17080), and the residual values on which entropy decoding has beenperformed by the entropy decoder 17010, that is, the quantized transformcoefficients and related parameter information, may be input to theinverse quantizer 17020. In addition, information about filtering of theinformation decoded by the entropy decoder 17010 may be provided to thefilter 17050. A receiver (not shown) configured to receive a signaloutput from the encoder may be further configured as aninternal/external element of the decoder 17000. Alternatively, thereceiver may be a component of the entropy decoder 17010.

The inverse quantizer 17020 may output transform coefficients byinversely quantizing the quantized transform coefficients. The inversequantizer 17020 may rearrange the quantized transform coefficients inthe form of a two-dimensional block. In this case, the rearrangement maybe performed based on the coefficient scan order implemented by theencoder. The inverse quantizer 17020 may perform inverse quantization onthe quantized transform coefficients using a quantization parameter(e.g., quantization step size information), and acquire transformcoefficients.

The inverse transformer 17030 acquires a residual signal (residual blockand residual sample array) by inversely transforming the transformcoefficients.

The predictor may perform prediction on the current block and generate apredicted block including prediction samples for the current block. Thepredictor may determine whether intra-prediction or inter-prediction isto be applied to the current block based on the information about theprediction output from the entropy decoder 17010, and may determine aspecific intra-/inter-prediction mode.

The intra-predictor 265 may predict the current block with reference tothe samples in the current picture. The samples may be positioned in theneighbor of or away from the current block depending on the predictionmode. In intra-prediction, the prediction modes may include a pluralityof non-directional modes and a plurality of directional modes. Theintra-predictor 17080 may determine a prediction mode to be applied tothe current block, using the prediction mode applied to the neighboringblock.

The inter-predictor 17070 may derive a predicted block for the currentblock based on a reference block (reference sample array) specified by amotion vector on the reference picture. In this case, in order to reducethe amount of motion information transmitted in the inter-predictionmode, the motion information may be predicted on a per block, subblock,or sample basis based on the correlation in motion information betweenthe neighboring blocks and the current block. The motion information mayinclude a motion vector and a reference picture index. The motioninformation may further include information about an inter-predictiondirection (L0 prediction, L1 prediction, Bi prediction, etc.). In thecase of inter-prediction, the neighboring blocks may include a spatialneighboring block, which is present in the current picture, and atemporal neighboring block, which is present in the reference picture.For example, the inter-predictor 17070 may configure a motioninformation candidate list based on neighboring blocks and derive amotion vector of the current block and/or a reference picture indexbased on the received candidate selection information. Inter-predictionmay be performed based on various prediction modes. The informationabout the prediction may include information indicating aninter-prediction mode for the current block.

The adder 17040 may add the acquired residual signal to the predictionsignal (predicted block or prediction sample array) output from theinter-predictor 17070 or the intra-predictor 17080, thereby generating areconstructed signal (a reconstructed picture, a reconstructed block, ora reconstructed sample array). When there is no residual signal for aprocessing target block as in the case where the skip mode is applied,the predicted block may be used as the reconstructed block.

The adder 17040 may be called a reconstructor or a reconstructed blockgenerator. The generated reconstructed signal may be used forintra-prediction of the next processing target block in the currentpicture, or may be used for inter-prediction of the next picture throughfiltering as described below.

The filter 17050 may improve subjective/objective image quality byapplying filtering to the reconstructed signal. For example, the filter17050 may generate a modified reconstructed picture by applying variousfiltering techniques to the reconstructed picture, and may transmit themodified reconstructed picture to the memory 250, specifically, the DPBof the memory 17060. The various filtering techniques may include, forexample, deblocking filtering, sample adaptive offset, adaptive loopfiltering, and bilateral filtering.

The reconstructed picture stored in the DPB of the memory 17060 may beused as a reference picture in the inter-predictor 17070. The memory17060 may store the motion information about a block from which themotion information is derived (or decoded) in the current picture and/orthe motion information about the blocks in a picture that has alreadybeen reconstructed. The stored motion information may be delivered tothe inter-predictor 17070 so as to be used as the motion informationabout a spatial neighboring block or the motion information about atemporal neighboring block. The memory 17060 may store the reconstructedsamples of the reconstructed blocks in the current picture, and deliverthe reconstructed samples to the intra-predictor 17080.

In the present disclosure, the embodiments described regarding thefilter 160, the inter-predictor 180, and the intra-predictor 185 of theencoding device 100 may be applied to the filter 17050, theinter-predictor 17070 and the intra-predictor 17080 of the decoder17000, respectively, in the same or corresponding manner.

At least one of the prediction, transform, and quantization proceduresdescribed above may be skipped. For example, for a block to which thepulse coding mode (PCM) is applied, the prediction, transform, andquantization procedures may be skipped, and the value of a decodedsample may be used as a sample of the reconstructed image.

Occupancy Map Decompression (16003)

This is a reverse process of the occupancy map compression describedabove. Occupancy map decompression is a process for reconstructing theoccupancy map by decompressing the occupancy map bitstream.

Auxiliary Patch Info Decompression (16004)

The auxiliary patch information may be reconstructed by performing thereverse process of the aforementioned auxiliary patch info compressionand decoding the compressed auxiliary patch info bitstream.

Geometry Reconstruction (16005)

This is a reverse process of the geometry image generation describedabove. Initially, a patch is extracted from the geometry image using thereconstructed occupancy map, the 2D position/size information about thepatch included in the auxiliary patch info, and the information aboutmapping between a block and the patch. Then, a point cloud isreconstructed in a 3D space based on the geometry image of the extractedpatch and the 3D position information about the patch included in theauxiliary patch info. When the geometry value corresponding to a point(u, v) within the patch is g(u, v), and the coordinates of the positionof the patch on the normal, tangent and bitangent axes of the 3D spaceare (□0, s0, r0), □(u, v), s(u, v), and r(u, v), which are the normal,tangent, and bitangent coordinates in the 3D space of a position mappedto point (u, v) may be expressed as follows:

□(u,v)=□0+g(u,v);

s(u,v)=s0+u;

r(u,v)=r0+v.

Smoothing (16006)

Smoothing, which is the same as the smoothing in the encoding processdescribed above, is a process for eliminating discontinuity that mayoccur on the patch boundary due to deterioration of the image qualityoccurring during the compression process.

Texture Reconstruction (16007)

Texture reconstruction is a process of reconstructing a color pointcloud by assigning color values to each point constituting a smoothedpoint cloud. It may be performed by assigning color values correspondingto a texture image pixel at the same position as in the geometry imagein the 2D space to points of a point of a point cloud corresponding tothe same position in the 3D space, based on the mapping informationabout the geometry image and the point cloud in the geometryreconstruction process described above.

Color Smoothing (16008)

Color smoothing is similar to the process of geometry smoothingdescribed above. Color smoothing is a process for eliminatingdiscontinuity that may occur on the patch boundary due to deteriorationof the image quality occurring during the compression process. Colorsmoothing may be performed through the following operations:

1) Calculate neighboring points of each point constituting thereconstructed point cloud using the K-D tree or the like. Theneighboring point information calculated in the geometry smoothingprocess described in section 2.5 may be used.

2) Determine whether each of the points is positioned on the patchboundary. These operations may be performed based on the boundaryinformation calculated in the geometry smoothing process describedabove.

3) Check the distribution of color values for the neighboring points ofthe points present on the boundary and determine whether smoothing is tobe performed. For example, when the entropy of luminance values is lessthan or equal to a threshold local entry (there are many similarluminance values), it may be determined that the corresponding portionis not an edge portion, and smoothing may be performed. As a method ofsmoothing, the color value of the point may be replaced with the averageof the color values of the neighboring points.

FIG. 18 is a flowchart illustrating operation of a transmission deviceaccording to embodiments of the present disclosure.

The transmission device according to the embodiments may correspond tothe transmission device of FIG. 1, the encoding process of FIG. 4, andthe 2D video/image encoder of FIG. 15, or perform some/all of theoperations thereof. Each component of the transmission device maycorrespond to software, hardware, a processor and/or a combinationthereof.

An operation process of the transmission terminal for compression andtransmission of point cloud data using V-PCC may be performed asillustrated in the figure.

The point cloud data transmission device according to the embodimentsmay be referred to as a transmission device.

Regarding a patch generator 18000, a patch for 2D image mapping of apoint cloud is generated. Auxiliary patch information is generated as aresult of the patch generation. The generated information may be used inthe processes of geometry image generation, texture image generation,and geometry reconstruction for smoothing.

Regarding a patch packer 18001, a patch packing process of mapping thegenerated patches into the 2D image is performed. As a result of patchpacking, an occupancy map may be generated. The occupancy map may beused in the processes of geometry image generation, texture imagegeneration, and geometry reconstruction for smoothing.

A geometry image generator 18002 generates a geometry image based on theauxiliary patch information and the occupancy map. The generatedgeometry image is encoded into one bitstream through video encoding.

An encoding preprocessor 18003 may include an image padding procedure.The geometry image regenerated by decoding the generated geometry imageor the encoded geometry bitstream may be used for 3D geometryreconstruction and then be subjected to a smoothing process.

A texture image generator 18004 may generate a texture image based onthe (smoothed) 3D geometry, the point cloud, the auxiliary patchinformation, and the occupancy map. The generated texture image may beencoded into one video bitstream.

A metadata encoder 18005 may encode the auxiliary patch information intoone metadata bitstream.

A video encoder 18006 may encode the occupancy map into one videobitstream.

A multiplexer 18007 may multiplex the video bitstreams of the generatedgeometry image, texture image, and occupancy map and the metadatabitstream of the auxiliary patch information into one bitstream.

A transmitter 18008 may transmit the bitstream to the receptionterminal. Alternatively, the video bitstreams of the generated geometryimage, texture image, and the occupancy map and the metadata bitstreamof the auxiliary patch information may be processed into a file of oneor more track data or encapsulated into segments and may be transmittedto the reception terminal through the transmitter.

FIG. 19 is a flowchart illustrating operation of a reception deviceaccording to embodiments.

The reception device according to the embodiments may correspond to thereception device of FIG. 1, the decoding process of FIG. 16, and the 2Dvideo/image encoder of FIG. 17, or perform some/all of the operationsthereof. Each component of the reception device may correspond tosoftware, hardware, a processor and/or a combination thereof.

The operation of the reception terminal for receiving and reconstructingpoint cloud data using V-PCC may be performed as illustrated in thefigure. The operation of the V-PCC reception terminal may follow thereverse process of the operation of the V-PCC transmission terminal ofFIG. 18.

The point cloud data reception device according to the embodiments maybe referred to as a reception device.

The bitstream of the received point cloud is demultiplexed into thevideo bitstreams of the compressed geometry image, texture image,occupancy map and the metadata bitstream of the auxiliary patchinformation by a demultiplexer 19000 after file/segment decapsulation. Avideo decoder 19001 and a metadata decoder 19002 decode thedemultiplexed video bitstreams and metadata bitstream. 3D geometry isreconstructed by a geometry reconstructor 19003 based on the decodedgeometry image, occupancy map, and auxiliary patch information, and isthen subjected to a smoothing process performed by a smoother 19004. Acolor point cloud image/picture may be reconstructed by a texturereconstructor 19005 by assigning color values to the smoothed 3Dgeometry based on the texture image. Thereafter, a color smoothingprocess may be additionally performed to improve theobjective/subjective visual quality, and a modified point cloudimage/picture derived through the color smoothing process is shown tothe user through the rendering process (through, for example, the pointcloud renderer). In some cases, the color smoothing process may beskipped.

FIG. 20 illustrates an exemplary architecture for V-PCC based storageand streaming of point cloud data according to embodiments.

A part/the entirety of the system of FIG. 20 may include some or all ofthe transmission device and reception device of FIG. 1, the encodingprocess of FIG. 4, the 2D video/image encoder of FIG. 15, the decodingprocess of FIG. 16, the transmission device of FIG. 18, and/or thereception device of FIG. 19. Each component in the figure may correspondto software, hardware, a processor and/or a combination thereof.

FIGS. 20 to 22 are diagrams illustrating a structure in which a systemis additionally connected to the transmission device and the receptiondevice according to embodiments. The transmission device and thereception device the system according to embodiments may be referred toas a transmission/reception apparatus according to the embodiments.

In the apparatus according to the embodiments illustrated in FIGS. 20 to22, the transmitting device corresponding to FIG. 18 or the like maygenerate a container suitable for a data format for transmission of abitstream containing encoded point cloud data.

The V-PCC system according to the embodiments may create a containerincluding point cloud data, and may further add additional datanecessary for efficient transmission/reception to the container.

The reception device according to the embodiments may receive and parsethe container based on the system shown in FIGS. 20 to 22. The receptiondevice corresponding to FIG. 19 or the like may decode and restore pointcloud data from the parsed bitstream.

The figure shows the overall architecture for storing or streaming pointcloud data compressed based on video-based point cloud compression(V-PCC). The process of storing and streaming the point cloud data mayinclude an acquisition process, an encoding process, a transmissionprocess, a decoding process, a rendering process, and/or a feedbackprocess.

The embodiments propose a method of effectively providing point cloudmedia/content/data.

In order to effectively provide point cloud media/content/data, a pointcloud acquirer 20000 may acquire a point cloud video. For example, oneor more cameras may acquire point cloud data through capture,composition or generation of a point cloud. Through this acquisitionprocess, a point cloud video including a 3D position (which may berepresented by x, y, and z position values, etc.) (hereinafter referredto as geometry) of each point and attributes (color, reflectance,transparency, etc.) of each point may be acquired. For example, aPolygon File format (PLY) (or Stanford Triangle format) file or the likecontaining the point cloud video may be generated. For point cloud datahaving multiple frames, one or more files may be acquired. In thisprocess, point cloud related metadata (e.g., metadata related tocapture, etc.) may be generated.

Post-processing for improving the quality of the content may be neededfor the captured point cloud video. In the video capture process, themaximum/minimum depth may be adjusted within the range provided by thecamera equipment. Even after the adjustment, point data of an unwantedarea may still be present. Accordingly, post-processing of removing theunwanted area (e.g., the background) or recognizing a connected spaceand filling the spatial holes may be performed. In addition, pointclouds extracted from the cameras sharing a spatial coordinate systemmay be integrated into one piece of content through the process oftransforming each point into a global coordinate system based on thecoordinates of the location of each camera acquired through acalibration process. Thereby, a point cloud video with a high density ofpoints may be acquired.

A point cloud pre-processor 20001 may generate one or morepictures/frames of the point cloud video. Here, a picture/frame maygenerally represent a unit representing one image in a specific timeinterval. When points constituting the point cloud video is divided intoone or more patches (sets of points that constitute the point cloudvideo, wherein the points belonging to the same patch are adjacent toeach other in the 3D space and are mapped in the same direction amongthe planar faces of a 6-face bounding box when mapped to a 2D image) andmapped to a 2D plane, an occupancy map picture/frame of a binary map,which indicates presence or absence of data at the correspondingposition in the 2D plane with a value of 0 or 1 may be generated. Inaddition, a geometry picture/frame, which is in the form of a depth mapthat represents the information about the position (geometry) of eachpoint constituting the point cloud video on a patch-by-patch basis, maybe generated. A texture picture/frame, which represents the colorinformation about each point constituting the point cloud video on apatch-by-patch basis, may be generated. In this process, metadata neededto reconstruct the point cloud from the individual patches may begenerated. The metadata may include information about the patches, suchas the position and size of each patch in the 2D/3D space. Thesepictures/frames may be generated continuously in temporal order toconstruct a video stream or metadata stream.

A point cloud video encoder 20002 may encode one or more video streamsrelated to a point cloud video. One video may include multiple frames,and one frame may correspond to a still image/picture. In the presentdisclosure, the point cloud video may include a point cloudimage/frame/picture, and the term “point cloud video” may be usedinterchangeably with the point cloud video/frame/picture. The pointcloud video encoder may perform a video-based point cloud compression(V-PCC) procedure. The point cloud video encoder may perform a series ofprocedures such as prediction, transform, quantization, and entropycoding for compression and coding efficiency. The encoded data (encodedvideo/image information) may be output in the form of a bitstream. Basedon the V-PCC procedure, the point cloud video encoder may encode pointcloud video by dividing the same into a geometry video, an attributevideo, an occupancy map video, and metadata, for example, informationabout patches, as described below. The geometry video may include ageometry image, the attribute video may include an attribute image, andthe occupancy map video may include an occupancy map image. The patchdata, which is auxiliary information, may include patch relatedinformation. The attribute video/image may include a texturevideo/image.

A point cloud image encoder 20003 may encode one or more images relatedto a point cloud video. The point cloud image encoder may perform avideo-based point cloud compression (V-PCC) procedure. The point cloudimage encoder may perform a series of procedures such as prediction,transform, quantization, and entropy coding for compression and codingefficiency. The encoded image may be output in the form of a bitstream.Based on the V-PCC procedure, the point cloud image encoder may encodethe point cloud image by dividing the same into a geometry image, anattribute image, an occupancy map image, and metadata, for example,information about patches, as described below.

The point cloud video encoder and/or the point cloud image encoderaccording to the embodiments may generate a PCC bitstream (G-PCC and/orV-PCC bitstream) according to the embodiments.

According to embodiments, the video encoder 20002, the image encoder20003, the video decoding 20006, and the image decoding may be performedby one encoder/decoder as described above, and may be performed alongseparate paths as shown in the figure.

In file/segment encapsulation 20004, the encoded point cloud data and/orpoint cloud-related metadata may be encapsulated into a file or asegment for streaming. Here, the point cloud-related metadata may bereceived from the metadata processor or the like. The metadata processormay be included in the point cloud video/image encoder or may beconfigured as a separate component/module. The encapsulation processormay encapsulate the corresponding video/image/metadata in a file formatsuch as ISOBMFF or in the form of a DASH segment or the like. Accordingto an embodiment, the encapsulation processor may include the pointcloud metadata in the file format. The point cloud-related metadata maybe included, for example, in boxes at various levels on the ISOBMFF fileformat or as data in a separate track within the file. According to anembodiment, the encapsulation processor may encapsulate the pointcloud-related metadata into a file.

The encapsulation or encapsulator according to the embodiments maydivide the G-PCC/V-PCC bitstream into one or multiple tracks and storethe same in a file, and may also encapsulate signaling information forthis operation. In addition, the atlas stream included on theG-PCC/V-PCC bitstream may be stored as a track in the file, and relatedsignaling information may be stored. Furthermore, an SEI message presentin the G-PCC/V-PCC bitstream may be stored in a track in the file andrelated signaling information may be stored.

A transmission processor may perform processing of the encapsulatedpoint cloud data for transmission according to the file format. Thetransmission processor may be included in the transmitter or may beconfigured as a separate component/module. The transmission processormay process the point cloud data according to a transmission protocol.The processing for transmission may include processing for delivery overa broadcast network and processing for delivery through a broadband.According to an embodiment, the transmission processor may receive pointcloud-related metadata from the metadata processor as well as the pointcloud data, and perform processing of the point cloud video data fortransmission.

The transmitter may transmit a point cloud bitstream or a file/segmentincluding the bitstream to the receiver of the reception device over adigital storage medium or a network. For transmission, processingaccording to any transmission protocol may be performed. The dataprocessed for transmission may be delivered over a broadcast networkand/or through a broadband. The data may be delivered to the receptionside in an on-demand manner. The digital storage medium may includevarious storage media such as USB, SD, CD, DVD, Blu-ray, HDD, and SSD.The transmitter may include an element for generating a media file in apredetermined file format, and may include an element for transmissionover a broadcast/communication network. The receiver may extract thebitstream and transmit the extracted bitstream to the decoder.

The receiver may receive point cloud data transmitted by the point clouddata transmission device according to the present disclosure. Dependingon the transmission channel, the receiver may receive the point clouddata over a broadcast network or through a broadband. Alternatively, thepoint cloud data may be received through the digital storage medium. Thereceiver may include a process of decoding the received data andrendering the data according to the viewport of the user.

The reception processor may perform processing on the received pointcloud video data according to the transmission protocol. The receptionprocessor may be included in the receiver or may be configured as aseparate component/module. The reception processor may reversely performthe process of the transmission processor above described so as tocorrespond to the processing for transmission performed at thetransmission side. The reception processor may deliver the acquiredpoint cloud video to a decapsulation processor, and the acquired pointcloud-related metadata to a metadata parser.

A decapsulation processor (file/segment decapsulation) 20005 maydecapsulate the point cloud data received in the form of a file from thereception processor. The decapsulation processor may decapsulate filesaccording to ISOBMFF or the like, and may acquire a point cloudbitstream or point cloud-related metadata (or a separate metadatabitstream). The acquired point cloud bitstream may be delivered to thepoint cloud decoder, and the acquired point cloud video-related metadata(metadata bitstream) may be delivered to the metadata processor. Thepoint cloud bitstream may include the metadata (metadata bitstream). Themetadata processor may be included in the point cloud decoder or may beconfigured as a separate component/module. The point cloud video-relatedmetadata acquired by the decapsulation processor may take the form of abox or track in the file format. The decapsulation processor may receivemetadata necessary for decapsulation from the metadata processor, whennecessary. The point cloud-related metadata may be delivered to thepoint cloud decoder and used in a point cloud decoding procedure, or maybe transferred to the renderer and used in a point cloud renderingprocedure.

The point cloud video decoder 20006 may receive the bitstream and decodethe video/image by performing an operation corresponding to theoperation of the point cloud video encoder. In this case, the pointcloud video decoder may decode the point cloud video by dividing thesame into a geometry video, an attribute video, an occupancy map video,and auxiliary patch information as described below. The geometry videomay include a geometry image, the attribute video may include anattribute image, and the occupancy map video may include an occupancymap image. The auxiliary information may include auxiliary patchinformation. The attribute video/image may include a texturevideo/image.

The 3D geometry may be reconstructed based on the decoded geometryimage, the occupancy map, and auxiliary patch information, and then maybe subjected to a smoothing process. The color point cloud image/picturemay be reconstructed by assigning a color value to the smoothed 3Dgeometry based on the texture image. The renderer may render thereconstructed geometry and the color point cloud image/picture. Therendered video/image may be displayed through the display. All or partof the rendered result may be shown to the user through a VR/AR displayor a typical display.

A sensor/tracker (sensing/tracking) 20007 acquires orientationinformation and/or user viewport information from the user or thereception side and delivers the orientation information and/or the userviewport information to the receiver and/or the transmitter. Theorientation information may represent information about the position,angle, movement, etc. of the user's head, or represent information aboutthe position, angle, movement, etc. of a device through which the useris viewing a video/image. Based on this information, information aboutthe area currently viewed by the user in a 3D space, that is, viewportinformation may be calculated.

The viewport information may be information about an area in a 3D spacecurrently viewed by the user through a device or an HMD. A device suchas a display may extract a viewport area based on the orientationinformation, a vertical or horizontal FOV supported by the device, andthe like. The orientation or viewport information may be extracted orcalculated at the reception side. The orientation or viewportinformation analyzed at the reception side may be transmitted to thetransmission side on a feedback channel.

Based on the orientation information acquired by the sensor/trackerand/or the viewport information indicating the area currently viewed bythe user, the receiver may efficiently extract or decode only media dataof a specific area, i.e., the area indicated by the orientationinformation and/or the viewport information from the file. In addition,based on the orientation information and/or viewport informationacquired by the sensor/tracker, the transmitter may efficiently encodeonly the media data of the specific area, that is, the area indicated bythe orientation information and/or the viewport information, or generateand transmit a file therefor.

The renderer may render the decoded point cloud data in a 3D space. Therendered video/image may be displayed through the display. The user mayview all or part of the rendered result through a VR/AR display or atypical display.

The feedback process may include transferring various kinds of feedbackinformation that may be acquired in the rendering/displaying process tothe transmitting side or the decoder of the receiving side. Through thefeedback process, interactivity may be provided in consumption of pointcloud data. According to an embodiment, head orientation information,viewport information indicating an area currently viewed by a user, andthe like may be delivered to the transmitting side in the feedbackprocess. According to an embodiment, the user may interact with what isimplemented in the VR/AR/MR/self-driving environment. In this case,information related to the interaction may be delivered to thetransmitting side or a service provider in the feedback process.According to an embodiment, the feedback process may be skipped.

According to an embodiment, the above-described feedback information maynot only be transmitted to the transmitting side, but also be consumedat the receiving side. That is, the decapsulation processing, decoding,and rendering processes at the receiving side may be performed based onthe above-described feedback information. For example, the point clouddata about the area currently viewed by the user may be preferentiallydecapsulated, decoded, and rendered based on the orientation informationand/or the viewport information.

FIG. 21 is an exemplary block diagram of a device for storing andtransmitting point cloud data according to embodiments.

FIG. 21 shows a point cloud system according to embodiments. A part/theentirety of the system may include some or all of the transmissiondevice and reception device of FIG. 1, the encoding process of FIG. 4,the 2D video/image encoder of FIG. 15, the decoding process of FIG. 16,the transmission device of FIG. 18, and/or the reception device of FIG.19. In addition, it may be included or corresponded to a part/theentirety of the system of FIG. 20.

A point cloud data transmission device according to embodiments may beconfigured as shown in the figure. Each element of the transmissiondevice may be a module/unit/component/hardware/software/a processor.

The geometry, attribute, auxiliary data, and mesh data of the pointcloud may each be configured as a separate stream or stored in differenttracks in a file. Furthermore, they may be included in a separatesegment.

A point cloud acquirer (point cloud acquisition) 21000 acquires a pointcloud. For example, one or more cameras may acquire point cloud datathrough capture, composition or generation of a point cloud. Throughthis acquisition process, point cloud data including a 3D position(which may be represented by x, y, and z position values, etc.)(hereinafter referred to as geometry) of each point and attributes(color, reflectance, transparency, etc.) of each point may be acquired.For example, a Polygon File format (PLY) (or Stanford Triangle format)file or the like including the point cloud data may be generated. Forpoint cloud data having multiple frames, one or more files may beacquired. In this process, point cloud related metadata (e.g., metadatarelated to capture, etc.) may be generated.

A patch generator (or patch generation) 21002 generates patches from thepoint cloud data. The patch generator generates point cloud data orpoint cloud video as one or more pictures/frames. A picture/frame maygenerally represent a unit representing one image in a specific timeinterval. When points constituting the point cloud video is divided intoone or more patches (sets of points that constitute the point cloudvideo, wherein the points belonging to the same patch are adjacent toeach other in the 3D space and are mapped in the same direction amongthe planar faces of a 6-face bounding box when mapped to a 2D image) andmapped to a 2D plane, an occupancy map picture/frame in a binary map,which indicates presence or absence of data at the correspondingposition in the 2D plane with 0 or 1 may be generated. In addition, ageometry picture/frame, which is in the form of a depth map thatrepresents the information about the position (geometry) of each pointconstituting the point cloud video on a patch-by-patch basis, may begenerated. A texture picture/frame, which represents the colorinformation about each point constituting the point cloud video on apatch-by-patch basis, may be generated. In this process, metadata neededto reconstruct the point cloud from the individual patches may begenerated. The metadata may include information about the patches, suchas the position and size of each patch in the 2D/3D space. Thesepictures/frames may be generated continuously in temporal order toconstruct a video stream or metadata stream.

In addition, the patches may be used for 2D image mapping. For example,the point cloud data may be projected onto each face of a cube. Afterpatch generation, a geometry image, one or more attribute images, anoccupancy map, auxiliary data, and/or mesh data may be generated basedon the generated patches.

Geometry image generation, attribute image generation, occupancy mapgeneration, auxiliary data generation, and/or mesh data generation areperformed by a pre-processor or a controller.

In geometry image generation 21002, a geometry image is generated basedon the result of the patch generation. Geometry represents a point in a3D space. The geometry image is generated using the occupancy map, whichincludes information related to 2D image packing of the patches,auxiliary data (patch data), and/or mesh data based on the patches. Thegeometry image is related to information such as a depth (e.g., near,far) of the patch generated after the patch generation.

In attribute image generation 21003, an attribute image is generated.For example, an attribute may represent a texture. The texture may be acolor value that matches each point. According to embodiments, images ofa plurality of attributes (such as color and reflectance) (N attributes)including a texture may be generated. The plurality of attributes mayinclude material information and reflectance. According to anembodiment, the attributes may additionally include informationindicating a color, which may vary depending on viewing angle and lighteven for the same texture.

In occupancy map generation 21004, an occupancy map is generated fromthe patches. The occupancy map includes information indicating presenceor absence of data in the pixel, such as the corresponding geometry orattribute image.

In auxiliary data generation 21005, auxiliary data including informationabout the patches is generated. That is, the auxiliary data representsmetadata about a patch of a point cloud object. For example, it mayrepresent information such as normal vectors for the patches.Specifically, the auxiliary data may include information needed toreconstruct the point cloud from the patches (e.g., information aboutthe positions, sizes, and the like of the patches in 2D/3D space, andprojection (normal) plane identification information, patch mappinginformation, etc.)

In mesh data generation 21006, mesh data is generated from the patches.Mesh represents connection between neighboring points. For example, itmay represent data of a triangular shape. For example, the mesh datarefers to connectivity between the points.

A point cloud pre-processor or controller generates metadata related topatch generation, geometry image generation, attribute image generation,occupancy map generation, auxiliary data generation, and mesh datageneration.

The point cloud transmission device performs video encoding and/or imageencoding in response to the result generated by the pre-processor. Thepoint cloud transmission device may generate point cloud image data aswell as point cloud video data. According to embodiments, the pointcloud data may have only video data, only image data, and/or both videodata and image data.

A video encoder 21007 performs geometry video compression, attributevideo compression, occupancy map compression, auxiliary datacompression, and/or mesh data compression. The video encoder generatesvideo stream(s) containing encoded video data.

Specifically, in the geometry video compression, point cloud geometryvideo data is encoded. In the attribute video compression, attributevideo data of the point cloud is encoded. In the auxiliary datacompression, auxiliary data associated with the point cloud video datais encoded. In the mesh data compression, mesh data of the point cloudvideo data is encoded. The respective operations of the point cloudvideo encoder may be performed in parallel.

An image encoder 21008 performs geometry image compression, attributeimage compression, occupancy map compression, auxiliary datacompression, and/or mesh data compression. The image encoder generatesimage(s) containing encoded image data.

Specifically, in the geometry image compression, the point cloudgeometry image data is encoded. In the attribute image compression, theattribute image data of the point cloud is encoded. In the auxiliarydata compression, the auxiliary data associated with the point cloudimage data is encoded. In the mesh data compression, the mesh dataassociated with the point cloud image data is encoded. The respectiveoperations of the point cloud image encoder may be performed inparallel.

The video encoder and/or the image encoder may receive metadata from thepre-processor. The video encoder and/or the image encoder may performeach encoding process based on the metadata.

A file/segment encapsulator (file/segment encapsulation) 21009encapsulates the video stream(s) and/or image(s) in the form of a fileand/or segment. The file/segment encapsulator performs video trackencapsulation, metadata track encapsulation, and/or image encapsulation.

In the video track encapsulation, one or more video streams may beencapsulated into one or more tracks.

In the metadata track encapsulation, metadata related to a video streamand/or an image may be encapsulated in one or more tracks. The metadataincludes data related to the content of the point cloud data. Forexample, it may include initial viewing orientation metadata. Accordingto embodiments, the metadata may be encapsulated into a metadata track,or may be encapsulated together in a video track or an image track.

In the image encapsulation, one or more images may be encapsulated intoone or more tracks or items.

For example, according to embodiments, when four video streams and twoimages are input to the encapsulator, the four video streams and twoimages may be encapsulated in one file.

The point cloud video encoder and/or the point cloud image encoderaccording to the embodiments may generate a G-PCC/V-PCC bitstreamaccording to the embodiments.

The file/segment encapsulator may receive metadata from thepre-processor. The file/segment encapsulator may perform encapsulationbased on the metadata.

A file and/or a segment generated by the file/segment encapsulation aretransmitted by the point cloud transmission device or the transmitter.For example, the segment(s) may be delivered based on a DASH-basedprotocol.

The encapsulation or encapsulator according to the embodiments maydivide the V-PCC bitstream into one or multiple tracks and store thesame in a file, and may also encapsulate signaling information for thisoperation. In addition, the atlas stream included on the V-PCC bitstreammay be stored as a track in the file, and related signaling informationmay be stored. Furthermore, an SEI message present in the V-PCCbitstream may be stored in a track in the file and related signalinginformation may be stored.

The transmitter may transmit a point cloud bitstream or a file/segmentincluding the bitstream to the receiver of the reception device over adigital storage medium or a network. Processing according to anytransmission protocol may be performed for transmission. The data thathas been processed for transmission may be delivered over a broadcastnetwork and/or through a broadband. The data may be delivered to thereceiving side in an on-demand manner. The digital storage medium mayinclude various storage media such as USB, SD, CD, DVD, Blu-ray, HDD,and SSD. The deliverer may include an element for generating a mediafile in a predetermined file format, and may include an element fortransmission over a broadcast/communication network. The delivererreceives orientation information and/or viewport information from thereceiver. The deliverer may deliver the acquired orientation informationand/or viewport information (or information selected by the user) to thepre-processor, the video encoder, the image encoder, the file/segmentencapsulator, and/or the point cloud encoder. Based on the orientationinformation and/or the viewport information, the point cloud encoder mayencode all point cloud data or the point cloud data indicated by theorientation information and/or the viewport information. Based on theorientation information and/or the viewport information, thefile/segment encapsulator may encapsulate all point cloud data or thepoint cloud data indicated by the orientation information and/or theviewport information. Based on the orientation information and/or theviewport information, the deliverer may deliver all point cloud data orthe point cloud data indicated by the orientation information and/or theviewport information.

For example, the pre-processor may perform the above-described operationon all the point cloud data or on the point cloud data indicated by theorientation information and/or the viewport information. The videoencoder and/or the image encoder may perform the above-describedoperation on all the point cloud data or on the point cloud dataindicated by the orientation information and/or the viewportinformation. The file/segment encapsulator may perform theabove-described operation on all the point cloud data or on the pointcloud data indicated by the orientation information and/or the viewportinformation. The transmitter may perform the above-described operationon all the point cloud data or on the point cloud data indicated by theorientation information and/or the viewport information.

FIG. 22 is an exemplary block diagram of a point cloud data receptiondevice according to embodiments.

FIG. 22 shows a point cloud system according to embodiments. A part/theentirety of the system may include some or all of the transmissiondevice and reception device of FIG. 1, the encoding process of FIG. 4,the 2D video/image encoder of FIG. 15, the decoding process of FIG. 16,the transmission device of FIG. 18, and/or the reception device of FIG.19. In addition, it may be included or corresponded to a part/theentirety of the system of FIGS. 20 and 21.

Each component of the reception device may be amodule/unit/component/hardware/software/processor. A delivery client mayreceive point cloud data, a point cloud bitstream, or a file/segmentincluding the bitstream transmitted by the point cloud data transmissiondevice according to the embodiments. The receiver may receive the pointcloud data over a broadcast network or through a broadband depending onthe channel used for the transmission. Alternatively, the point cloudvideo data may be received through a digital storage medium. Thereceiver may include a process of decoding the received data andrendering the received data according to the user viewport. Thereception processor may perform processing on the received point clouddata according to a transmission protocol. A reception processor may beincluded in the receiver or configured as a separate component/module.The reception processor may reversely perform the process of thetransmission processor described above so as to correspond to theprocessing for transmission performed at the transmitting side. Thereception processor may deliver the acquired point cloud data to thedecapsulation processor and the acquired point cloud related metadata tothe metadata parser.

The sensor/tracker (sensing/tracking) acquires orientation informationand/or viewport information. The sensor/tracker may deliver the acquiredorientation information and/or viewport information to the deliveryclient, the file/segment decapsulator, and the point cloud decoder.

The delivery client may receive all point cloud data or the point clouddata indicated by the orientation information and/or the viewportinformation based on the orientation information and/or the viewportinformation. The file/segment decapsulator may decapsulate all pointcloud data or the point cloud data indicated by the orientationinformation and/or the viewport information based on the orientationinformation and/or the viewport information. The point cloud decoder(the video decoder and/or the image decoder) may decode all point clouddata or the point cloud data indicated by the orientation informationand/or the viewport information based on the orientation informationand/or the viewport information. The point cloud processor may processall point cloud data or the point cloud data indicated by theorientation information and/or the viewport information based on theorientation information and/or the viewport information.

A file/segment decapsulator (file/segment decapsulation) 22000 performsvideo track decapsulation, metadata track decapsulation, and/or imagedecapsulation. The decapsulation processor (file/segment decapsulation)may decapsulate the point cloud data in the form of a file received fromthe reception processor. The decapsulation processor (file/segmentdecapsulation) may decapsulate files or segments according to ISOBMFF,etc., to acquire a point cloud bitstream or point cloud-related metadata(or a separate metadata bitstream). The acquired point cloud bitstreammay be delivered to the point cloud decoder, and the acquired pointcloud-related metadata (or metadata bitstream) may be delivered to themetadata processor. The point cloud bitstream may include the metadata(metadata bitstream). The metadata processor may be included in thepoint cloud video decoder or may be configured as a separatecomponent/module. The point cloud-related metadata acquired by thedecapsulation processor may take the form of a box or track in a fileformat. The decapsulation processor may receive metadata necessary fordecapsulation from the metadata processor, when necessary. The pointcloud-related metadata may be delivered to the point cloud decoder andused in a point cloud decoding procedure, or may be delivered to therenderer and used in a point cloud rendering procedure. The file/segmentdecapsulator may generate metadata related to the point cloud data.

In the video track decapsulation, a video track contained in the fileand/or segment is decapsulated. Video stream(s) including a geometryvideo, an attribute video, an occupancy map, auxiliary data, and/or meshdata are decapsulated.

In the metadata track decapsulation, a bitstream containing metadatarelated to the point cloud data and/or auxiliary data is decapsulated.

In the image decapsulation, image(s) including a geometry image, anattribute image, an occupancy map, auxiliary data and/or mesh data aredecapsulated.

The decapsulation or decapsulator according to the embodiments maydivide and parse (decapsulate) the G-PCC/V-PCC bitstream based on one ormore tracks in a file, and may also decapsulate signaling informationtherefor. In addition, the atlas stream included in the G-PCC/V-PCCbitstream may be decapsulated based on a track in the file, and relatedsignaling information may be parsed. Furthermore, an SEI message presentin the G-PCC/V-PCC bitstream may be decapsulated based on a track in thefile, and related signaling information may be also acquired.

The video decoding or video decoder 22001 performs geometry videodecompression, attribute video decompression, occupancy mapdecompression, auxiliary data decompression, and/or mesh datadecompression. The video decoder decodes the geometry video, theattribute video, the auxiliary data, and/or the mesh data in a processcorresponding to the process performed by the video encoder of the pointcloud transmission device according to the embodiments.

The image decoding or image decoder 22002 performs geometry imagedecompression, attribute image decompression, occupancy mapdecompression, auxiliary data decompression, and/or mesh datadecompression. The image decoder decodes the geometry image, theattribute image, the auxiliary data, and/or the mesh data in a processcorresponding to the process performed by the image encoder of the pointcloud transmission device according to the embodiments.

The video decoding and the image decoding according to the embodimentsmay be processed by one video/image decoder as described above, and maybe performed along separate paths as illustrated in the figure.

The video decoding and/or the image decoding may generate metadatarelated to the video data and/or the image data.

The point cloud video encoder and/or the point cloud image encoderaccording to the embodiments may decode the G-PCC/V-PCC bitstreamaccording to the embodiments.

In point cloud processing 22003, geometry reconstruction and/orattribute reconstruction are performed.

In the geometry reconstruction, the geometry video and/or geometry imageare reconstructed from the decoded video data and/or decoded image databased on the occupancy map, auxiliary data and/or mesh data.

In the attribute reconstruction, the attribute video and/or theattribute image are reconstructed from the decoded attribute videoand/or the decoded attribute image based on the occupancy map, auxiliarydata, and/or mesh data. According to embodiments, for example, theattribute may be a texture. According to embodiments, an attribute mayrepresent a plurality of pieces of attribute information. When there isa plurality of attributes, the point cloud processor according to theembodiments performs a plurality of attribute reconstructions.

The point cloud processor may receive metadata from the video decoder,the image decoder, and/or the file/segment decapsulator, and process thepoint cloud based on the metadata.

The point cloud rendering or point cloud renderer renders thereconstructed point cloud. The point cloud renderer may receive metadatafrom the video decoder, the image decoder, and/or the file/segmentdecapsulator, and render the point cloud based on the metadata.

The display actually displays the result of rendering on the display.

As shown in FIGS. 15 to 19, after encoding/decoding, the method/deviceaccording to the embodiments the point cloud data as shown in 15 to 19,the bitstream containing the point cloud data may be encapsulated and/ordecapsulated in the form of a file and/or a segment.

For example, a point cloud data device according to the embodiments mayencapsulate point cloud data based on a file. The file may include aV-PCC track containing parameters for a point cloud, a geometry trackcontaining geometry, an attribute track containing an attribute, and anoccupancy track containing an occupancy map.

In addition, a point cloud data reception device according toembodiments decapsulates the point cloud data based on a file. The filemay include a V-PCC track containing parameters for a point cloud, ageometry track containing geometry, an attribute track containing anattribute, and an occupancy track containing an occupancy map.

The operation described above may be performed by the file/segmentencapsulator 20004 of FIG. 20, the file/segment encapsulator 21009 ofFIG. 21, and the file/segment encapsulator 22000 of FIG. 22.

FIG. 23 illustrates an exemplary structure operable in connection withpoint cloud data transmission/reception methods/devices according toembodiments.

In the structure according to the embodiments, at least one of a server2360, a robot 2310, a self-driving vehicle 2320, an XR device 2330, asmartphone 2340, a home appliance 2350 and/or a head-mount display (HMD)2370 is connected to a cloud network 2300. Here, the robot 2310, theself-driving vehicle 2320, the XR device 2330, the smartphone 2340, orthe home appliance 2350 may be referred to as a device. In addition, theXR device 1730 may correspond to a point cloud data (PCC) deviceaccording to embodiments or may be operatively connected to the PCCdevice.

The cloud network 2300 may represent a network that constitutes part ofthe cloud computing infrastructure or is present in the cloud computinginfrastructure. Here, the cloud network 2300 may be configured using a3G network, 4G or Long Term Evolution (LTE) network, or a 5G network.

The server 2360 may be connected to at least one of the robot 2310, theself-driving vehicle 2320, the XR device 2330, the smartphone 2340, thehome appliance 2350, and/or the HMD 2370 over the cloud network 2300 andmay assist at least a part of the processing of the connected devices2310 to 2370.

The HMD 2370 represents one of the implementation types of the XR deviceand/or the PCC device according to the embodiments. An HMD type deviceaccording to embodiments includes a communication unit, a control unit,a memory, an I/O unit, a sensor unit, and a power supply unit.

Hereinafter, various embodiments of the devices 2310 to 2350 to whichthe above-described technology is applied will be described. The devices2310 to 2350 illustrated in FIG. 23 may be operatively connected/coupledto a point cloud data transmission and reception device according to theabove-described embodiments.

<PCC+XR>

The XR/PCC device 2330 may employ PCC technology and/or XR (AR+VR)technology, and may be implemented as an HMD, a head-up display (HUD)provided in a vehicle, a television, a mobile phone, a smartphone, acomputer, a wearable device, a home appliance, a digital signage, avehicle, a stationary robot, or a mobile robot.

The XR/PCC device 2330 may analyze 3D point cloud data or image dataacquired through various sensors or from an external device and generateposition data and attribute data about 3D points. Thereby, the XR/PCCdevice 2330 may acquire information about the surrounding space or areal object, and render and output an XR object. For example, the XR/PCCdevice 2330 may match an XR object including auxiliary information abouta recognized object with the recognized object and output the matched XRobject.

<PCC+XR+Mobile Phone>

The XR/PCC device 2330 may be implemented as a mobile phone 2340 byapplying PCC technology.

The mobile phone 2340 may decode and display point cloud content basedon the PCC technology.

<PCC+Self-Driving+XR>

The self-driving vehicle 2320 may be implemented as a mobile robot, avehicle, an unmanned aerial vehicle, or the like by applying the PCCtechnology and the XR technology.

The self-driving vehicle 2320 to which the XR/PCC technology is appliedmay represent an autonomous vehicle provided with means for providing anXR image, or an autonomous vehicle that is a target ofcontrol/interaction in the XR image. In particular, the self-drivingvehicle 2320, which is a target of control/interaction in the XR image,may be distinguished from the XR device 2330 and may be operativelyconnected thereto.

The self-driving vehicle 2320 having means for providing an XR/PCC imagemay acquire sensor information from the sensors including a camera, andoutput the generated XR/PCC image based on the acquired sensorinformation. For example, the self-driving vehicle may have an HUD andoutput an XR/PCC image thereto to provide an occupant with an XR/PCCobject corresponding to a real object or an object present on thescreen.

In this case, when the XR/PCC object is output to the HUD, at least apart of the XR/PCC object may be output to overlap the real object towhich the occupant's eyes are directed. On the other hand, when theXR/PCC object is output on a display provided inside the self-drivingvehicle, at least a part of the XR/PCC object may be output to overlapthe object on the screen. For example, the self-driving vehicle mayoutput XR/PCC objects corresponding to objects such as a road, anothervehicle, a traffic light, a traffic sign, a two-wheeled vehicle, apedestrian, and a building.

The virtual reality (VR) technology, the augmented reality (AR)technology, the mixed reality (MR) technology and/or the point cloudcompression (PCC) technology according to the embodiments are applicableto various devices.

In other words, the VR technology is a display technology that providesonly real-world objects, backgrounds, and the like as CG images. On theother hand, the AR technology refers to a technology for showing a CGimage virtually created on a real object image. The MR technology issimilar to the AR technology described above in that virtual objects tobe shown are mixed and combined with the real world. However, the MRtechnology differs from the AR technology makes a clear distinctionbetween a real object and a virtual object created as a CG image anduses virtual objects as complementary objects for real objects, whereasthe MR technology treats virtual objects as objects having the samecharacteristics as real objects. More specifically, an example of MRtechnology applications is a hologram service.

Recently, the VR, AR, and MR technologies are sometimes referred to asextended reality (XR) technology rather than being clearly distinguishedfrom each other. Accordingly, embodiments of the present disclosure areapplicable to all VR, AR, MR, and XR technologies. For suchtechnologies, encoding/decoding based on PCC, V-PCC, and G-PCCtechniques may be applied.

The PCC method/device according to the embodiments may be applied to avehicle that provides a self-driving service.

A vehicle that provides the self-driving service is connected to a PCCdevice for wired/wireless communication.

When the point cloud data transmission and reception device (PCC device)according to the embodiments is connected to a vehicle forwired/wireless communication, the device may receive and process contentdata related to an AR/VR/PCC service that may be provided together withthe self-driving service and transmit the processed content data to thevehicle. In the case where the point cloud data transmission andreception device is mounted on a vehicle, the point cloud transmittingand reception device may receive and process content data related to theAR/VR/PCC service according to a user input signal input through a userinterface device and provide the processed content data to the user. Thevehicle or the user interface device according to the embodiments mayreceive a user input signal. The user input signal according to theembodiments may include a signal indicating the self-driving service.

A point cloud data transmission method/device according to embodiments,an encoding operation and encoder of the transmission method/deviceaccording to embodiments, encapsulation and an encapsulator of the pointcloud data transmission method/device, a point cloud data receptionmethod/device, a decoding operation and decoder of the point cloud datareception method/device according to embodiments, decapsulation and adecapsulator of the point cloud data receiving method/device accordingto embodiments may be referred to simply as a method/device according toembodiments.

FIG. 24 shows a patch, an atlas, an atlas tile group, an atlas frame,and the like.

A method/device according to embodiments (e.g., FIGS. 1, 4, 15 to 23,etc.) may generate, transmit, and receive multiple V-PCC tracks formultiple atlas data. In addition, a file format definition for a methodof configuring one or more V-PCC tracks for a V-PCC bitstream containingmultiple atlas data or an atlas sub-bitstream, and a method forsignaling and receiving the same may be provided.

The method/device according to the embodiments (e.g., FIGS. 1, 4, 15 to23, etc.) is a transmitter (encoder) or a receiver (decoder) forprovision of a point cloud content service that efficiently stores aV-PCC bitstream in tracks of a file and provides signaling for the same.

The method/device according to the embodiments (e.g., FIGS. 1, 4, 15 to23, etc.) is related to a transmitter or receiver for provision of apoint cloud content service that processes a file storage technique tosupport efficient access to a V-PCC bitstream stored in a file.

The method/device according to the embodiments (e.g., FIGS. 1, 4, 15 to23, etc.) supports efficient storage of a V-PCC bitstream in a filetrack, signaling for the same, and efficient access to the stored V-PCCbitstream. In addition, the V-PCC bitstream may be divided and storedinto one or more tracks in a file by adding (or additionallymodifying/combining) a file storage technique therefor.

Definitions of terms according to embodiments are as follows. VPS: V-PCCparameter set; AD: atlas data; OVD: occupancy video data; GVD: geometryvideo data; AVD: attribute video data; ACL: atlas coding layer; AAPS:atlas adaptation parameter set; ASPS: atlas sequence parameter set; asyntax structure containing syntax elements that apply to zero or moreentire coded atlas sequences (CASs) as determined by the content of asyntax element found in the ASPS referred to by a syntax element foundin each tile group header; AFPS: atlas frame atlas frame parameter set;a syntax structure containing syntax elements that apply to zero or moreentire coded atlas frames as determined by the content of a syntaxelement found in the tile group header0; SEI: supplemental enhancementinformation; Atlas: this may be a collection of 2D bounding boxes, i.e.patches, projected into a rectangular frame that correspond to a3-dimensional bounding box in 3D space, which may represent a subset ofa point cloud, or collection of 2D bounding boxes and their associatedinformation placed onto a rectangular frame and corresponding to avolume in 3D space on which volumetric data is rendered; Atlassub-bitstream: an extracted sub-bitstream from the V-PCC bitstreamcontaining a part of an atlas NAL bitstream; V-PCC content: a pointcloud encoded using video-coded point cloud compression (V-PCC); V-PCCtrack: a volumetric visual track which carries the atlas bitstream ofthe V-PCC bitstream; V-PCC component track: video track which carries 2Dvideo encoded data for any of the occupancy map, geometry, or attributecomponent video bitstreams of the V-PCC bitstream.

The V-PCC bitstream for a point cloud object, which is a target of pointcloud data, may be composed of one or more atlas data.

Each atlas data may have vuh_atlas_id of the vpcc_unit_header( ) ofFIGS. 26 and 27. The atlas data and vuh_atlas_id may be mapped to eachother. The device according to the embodiments may acquire atlas datathrough vuh_atlas_id.

Each of the atlas data may have an association with one or more atlastile groups 24000 or atlas tile groups that may constitute an atlasframe 24001.

An atlas tile may be an atlas bitstream corresponding to the tile. Acollection of patches 24003 may be an atlas tile group, and a collectionof atlas tile groups may be an atlas frame.

Referring to FIG. 24, the method/device according to embodiments mayconfigure V-PCC content composed of multiple atlas sub-bitstreams inmultiple V-PCC tracks.

In general, three atlas tile groups may be configured in one atlas framesuch as an atlas frame 24002.

Reference numerals 24004 and 24005 according to embodiments representcases where multiple atlas data are configured. 24004 is a case whereone atlas data incudes one atlas tile group. 24005 is a case where oneatlas data includes one or more atlas tile groups.

The method/device according to the embodiments may process a singleatlas and/or multiple atlases, and may provide a data storage method anda signaling method for a single atlas and/or multiple atlases.

In the case of the single atlas 24002, a frame of point cloud dataacquired from a point cloud object may include one atlas. For example,the frame may include an atlas tile group or an atlas frame.

In the case of the multiple atlases 24004 and 24005, a frame of pointcloud data acquired from a point cloud object may include one atlas. Forexample, each of three atlases may include three atlas tile groups. Oneatlas may include an atlas frame, and the atlas frame may include anatlas tile group. Also, one of the two atlases may include one atlastile group, and the other atlas may include two atlas tile groups. Oneatlas frame may include an atlas tile group.

According to embodiments, the atlas frame may correspond to an atlas,and the atlas may be partitioned into tiles. A patch may be a 2Dbounding box on which a point cloud object is projected, and one or morepatches may be referred to as an atlas tile group. The atlas may beinformation related to a 2D bounding box and the 2D bounding box.

FIG. 25 shows a structure of a bitstream containing point cloud dataaccording to embodiments.

FIG. 25 is a structure of a bitstream containing point cloud dataaccording to embodiments to be encoded or decoded, as illustrated inFIGS. 15 to 23.

The method/device according to the embodiments generates a bitstream fora dynamic point cloud object. In this regard, a file format for thebitstream is proposed, and a signaling scheme therefor is provided.

The method/device according to the embodiments includes a transmitter, areceiver, and/or a processor for providing a point cloud content serviceof efficiently storing a V-PCC (=V3C) bitstream in a track of a file andproviding signaling therefor.

The method/device according to the embodiments provides a data formatfor storing a V-PCC bitstream containing point cloud data. Accordingly,the reception method/device according to the embodiments provides a datastorage and signaling method for receiving point cloud data andefficiently accessing the point cloud data. Therefore, based on thestorage technique for a file containing point cloud data for efficientaccess, the transmitter and/or the receiver may provide a point cloudcontent service.

FIG. 25 shows a structure of a point cloud bitstream contained in datatransmitted and received by the methods/devices according to theembodiments.

A method of compressing and decompressing point cloud data according toembodiments represent volumetric encoding and decoding of point cloudvisual information.

A point cloud bitstream (which may be referred to as a V-PCC bitstreamor V3C bitstream) 25000 containing a coded point cloud sequence (CPCS)may include sample stream V-PCC units 25010. The sample stream V-PCCunits 25010 may carry V-PCC parameter set (VPS) data 25020, an atlasbitstream 25030, a 2D video encoded occupancy map bitstream 25040, a 2Dvideo encoded geometry bitstream 25050, and zero or one or more 2D videoencoded attribute bitstreams 25060.

The point cloud bitstream 25000 may include a sample stream VPCC header25070.

ssvh_unit_size_precision_bytes_minus1: A value obtained by adding 1 tothis value specifies the precision, in bytes, of the ssvu_vpcc_unit_sizeelement in all sample stream V-PCC units.ssvh_unit_size_precision_bytes_minus1 may be in the range of 0 to 7.

The syntax 26080 of the sample stream V-PCC unit 26010 is configured asfollows. Each sample stream V-PCC unit may include a type of one ofV-PCC units of VPS, AD, OVD, GVD, and AVD. The content of each samplestream V-PCC unit may be associated with the same access unit as theV-PCC unit included in the sample stream V-PCC unit.

ssvu_vpcc_unit_size: specifies the size, in bytes, of the subsequentvpcc_unit. The number of bits used to represent ssvu_vpcc unit size isequal to

(ssvh_unit_size_precision_bytes_minus1+1)*8.

The method/device according to the embodiments receives the bitstream ofFIG. 25 containing the encoded point cloud data, and generates a file asshown in FIGS. 70 to 72 through the encapsulator 20004 or 21009.

The method/device according to the embodiments receives a file as shownin FIGS. 70 to 72 and decodes point cloud data through the decapsulator22000 or the like.

The VPS 25020 and/or the AD 25030 may be encapsulated in track-4 (V3Ctrack 70030). The OVD 25040 may be encapsulated in track-2 (occupancytrack 70010). The GVD 25050 may be encapsulated in track-3 (geometrytrack 70020). The AVD 25060 may be encapsulated in track-1 (attributetrack 70000).

FIG. 26 shows a structure of a bitstream containing point cloud dataaccording to embodiments.

A bitstream 26000 of FIG. 26 corresponds to the bitstream 25000 of FIG.25. The bitstream of FIGS. 25 and 26 is generated by the transmissiondevice 10000 of FIG. 1, the point cloud video encoder 10002 of FIG. 1,the encoder of FIG. 4, the encoder of FIG. 15, the transmission deviceof FIG. 18, the processor 20001 of FIG. 20, and the video/image encoder20002 of FIG. 20, the processors 21001 to 21006 of FIG. 21, thevideo/image encoders 21007 and 21008, and the like.

The bitstream of FIGS. 25 and 26 is stored in a container (the file inFIGS. 70 to 72) by the file/segment encapsulator of FIG. 1, thefile/segment encapsulator 20004 of FIG. 20, the file/segmentencapsulator 21009 of FIG. 21, or the like.

The bitstream of FIGS. 25 and 26 is transmitted by the transmitter 10004of FIG. 1 or the like.

The container (file in FIGS. 70 to 72) including the bitstream of FIGS.25 and 26 is received by the reception device 10005, the receiver 10006,or the like in FIG. 1.

The bitstream of FIGS. 25 and 26 is parsed from the container by thefile/segment decapsulator 10007 of FIG. 1, the file/segment decapsulator20005 of FIG. 20, the file/segment decapsulator 22000 of FIG. 22, or thelike.

The bitstream of FIGS. 25 and 26 is decoded and reconstructed andprovided to the user by the point cloud video decoder 10008 of FIG. 1,the decoder of FIG. 16, the decoder of FIG. 17, the reception device ofFIG. 19, the video/image decoder 20006 of FIG. 20, the video/imagedecoders 22001 and 22002 of FIG. 22, the processor 22003 of FIG. 22, orthe like.

The sample stream V-PCC unit contained in the bitstream 26000 related topoint cloud data according to the embodiments may include a V-PCC unitsize 26010 and a V-PCC unit 26020.

Each V-PCC unit 26020 may include a V-PCC unit header 26030 and a V-PCCunit payload 26040. The V-PCC unit header 26030 may describe a V-PCCunit type. The V-PCC unit header of attribute video data may describe anattribute type, an index thereof, multiple instances of the sameattribute type supported, and the like.

The unit payloads 26050, 26060, and 26070 of occupancy, geometry andattribute video data may correspond to video data units. For example,the occupancy video data, geometry video data, and attribute video data26050, 26060, and 26070 may be HEVC NAL units. Such video data may bedecoded by a video decoder according to embodiments.

FIG. 27 shows a V-PCC unit and a V-PCC unit header according toembodiments.

FIG. 27 shows the syntaxes of the V-PCC unit 26020 and the V-PCC unitheader 26030 illustrated in FIG. 26.

A V-PCC bitstream according to embodiments may contain a series of V-PCCsequences.

A V-PCC bitstream contains a series of V-PCC sequences. A vpcc unit typewith a value of vuh_unit_type equal to VPCC_VPS may be expected to bethe first V-PCC unit type in a V-PCC sequence. All other V-PCC unittypes follow this unit type without any additional restrictions in theircoding order. A V-PCC unit payload of a V-PCC unit carrying occupancyvideo, attribute video, or geometry video is composed of one or more NALunits.

A VPCC unit may include a header and a payload.

The VPCC unit header may include the following information based on theVUH unit type.

vuh_unit_type indicates the type of the V-PCC unit 26020 as follows.

vuh_unit_type Identifier V-PCC Unit Type Description 0 VPCC_VPS V-PCCparameter set V-PCC level parameters 1 VPCC_AD Atlas data Atlasinformation 2 VPCC_OVD Occupancy Video Data Occupancy information 3VPCC_GVD Geometry Video Data Geometry information 4 VPCC_AVD AttributeVideo Data Attribute information 5 . . . 31 VPCC_RSVD Reserved —

When vuh_unit_type indicates attribute video data (VPCC_AVD), geometryvideo data (VPCC_GVD), occupancy video data (VPCC_OVD), or atlas data(VPCC_AD) vuh_vpcc_parameter_set_ID and vuh_atlas_id is carried in theunit header. A parameter set ID and an atlas ID associated with theV-PCC unit may be delivered.

When the unit type is atlas video data, the header of the unit may carryan attribute index (vuh_attribute_index), an attribute partition index(vuh_attribute_partition_index), a map index (vuh_map_index), and anauxiliary video flag (vuh_auxiliary_video_flag).

When the unit type is geometry video data, vuh_map_index andvuh_auxiliary_video_flag may be carried.

When the unit type is occupancy video data or atlas data, the header ofthe unit may contain additional reserved bits.

vuh_vpcc_parameter_set_id specifies the value ofvps_vpcc_parameter_set_id for the active V-PCC VPS. Through thevpcc_parameter_set_id in the header of the current V-PCC unit, the ID ofthe VPS parameter set may be known and the relationship between theV-PCC unit and the V-PCC parameter set may be announced.

vuh_atlas_id specifies the index of the atlas that corresponds to thecurrent V-PCC unit. Through the vuh_atlas_id in the header of thecurrent V-PCC unit, the index of the atlas may be known, and the atlascorresponding to the V-PCC unit may be announced.

vuh_attribute_index indicates the index of the attribute data carried inthe Attribute Video Data unit.

vuh_attribute_partition_index indicates the index of the attributedimension group carried in the Attribute Video Data unit.

vuh_map_index indicates, when present, the map index of the currentgeometry or attribute stream.

vuh_auxiliary_video_flag equal to 1 indicates that the associatedgeometry or attribute video data unit is a RAW and/or EOM coded pointsvideo only. vuh_auxiliary_video_flag equal to 0 indicates that theassociated geometry or attribute video data unit may contain RAW and/orEOM coded points.

FIG. 28 shows the payload of a V-PCC unit according to embodiments.

FIG. 28 shows the syntax of the V-PCC unit payload 26040.

When vuh_unit_type is V-PCC parameter set (VPCC VPS), the V-PCC unitpayload contains vpcc_parameter_set( ).

When vuh_unit_type is V-PCC atlas data (VPCC_AD), the V-PCC unit payloadcontains atlas_sub_bitstream( ).

When vuh_unit_type is V-PCC accumulating video data (VPCC_OVD),geometric video data (VPCC_GVD), or attribute video data (VPCC_AVD), theV-PCC unit payload contains video_sub_bitstream( ).

Hereinafter, information contained in the payload of the V-PCC unit willbe described.

FIG. 29 shows a V-PCC parameter set according to embodiments.

FIG. 29 shows the syntax of a parameter set when the payload 26040 ofthe unit 26020 of the bitstream according to the embodiments containsthe parameter set as shown in FIG. 28.

The VPS of FIG. 29 may include the following elements.

profile_tier_level( ) specifies restrictions on the bitstreams and hencelimits on the capabilities needed to decode the bitstreams. Profiles,tiers, and levels may also be used to indicate interoperability pointsbetween individual decoder implementations.

vps_vpcc_parameter_set_id may provide an identifier for the V-PCC VPSfor reference by other syntax elements.

vps_atlas_count_minus1 plus 1 indicates the total number of supportedatlases in the current bitstream.

Depending on the number of atlases, the following parameters may befurther included in the parameter set.

vps_frame_width[j] indicates the V-PCC frame width in terms of integerluma samples for the atlas with index j. This frame width is the nominalwidth that is associated with all V-PCC components for the atlas withindex j.

vps_frame_height[j] indicates the V-PCC frame height in terms of integerluma samples for the atlas with index j. This frame height is thenominal height that is associated with all V-PCC components for theatlas with index j.

vps_map_count_minus1[j] plus 1 indicates the number of maps used forencoding the geometry and attribute data for the atlas with index j.

When vps_map_count_minus1[j] is greater than 0, the following parametersmay be further included in the parameter set.

Depending on the value of vps_map_count_minus1[j], the followingparameters may be further included in the parameter set.

vps_multiple_map_streams_present_flag[j] equal to 0 indicates that allgeometry or attribute maps for the atlas with index j are placed in asingle geometry or attribute video stream, respectively.vps_multiple_map_streams_present_flag[j] equal to 1 indicates that allgeometry or attribute maps for the atlas with index j are placed inseparate video streams.

If vps_multiple_map_streams_present_flag[j] indicates 1,vps_map_absolute_coding_enabled_flag[j][i] may be further included inthe parameter set. Otherwise, vps_map_absolute_coding_enabled_flag[j][i]may have a value of 1.

vps_map_absolute_coding_enabled_flag[j][i] equal to 1 indicates that thegeometry map with index i for the atlas with index j is coded withoutany form of map prediction. vps_map_absolute_coding_enabled_flag[j][i]equal to 0 indicates that the geometry map with index i for the atlaswith index j is first predicted from another, earlier coded map, priorto coding.

vps_map_absolute_coding_enabled_flag[j][0] equal to 1 indicates that thegeometry map with index 0 is coded without map prediction.

If vps_map_absolute_coding_enabled_flag[j][i] is 0 and i is greater than0, vps_map_predictor_index_diff[j][i] may be further included in theparameter set. Otherwise, vps_map_predictor_index_diff[j][i] may be 0.

vps_map_predictor_index_diff[j][i] is used to compute the predictor ofthe geometry map with index i for the atlas with index j whenvps_map_absolute_coding_enabled_flag[j][i] is equal to 0.

vps_auxiliary_video_present_flag[j] equal to 1 indicates that auxiliaryinformation for the atlas with index j, i.e. RAW or EOM patch data, maybe stored in a separate video stream, referred to as the auxiliary videostream. vps_auxiliary_video_present_flag[j] equal to 0 indicates thatauxiliary information for the atlas with index j is not be stored in aseparate video stream.

occupancy_information( ) includes occupancy video related information.

geometry_information( ) includes geometry video related information.

attribute_information( ) includes attribute video related information.

vps_extension_present_flag equal to 1 specifies that the syntax elementvps_extension_length is present in vpcc_parameter_set syntax structure.vps_extension_present_flag equal to 0 specifies that syntax elementvps_extension_length is not present.

vps_extension_length_minus1 plus 1 specifies the number ofvps_extension_data_byte elements that follow this syntax element.

Depending on vps_extension_length_minus1, extension data may be furtherincluded in the parameter set.

vps_extension_data_byte may have any value that may be included throughextension.

FIG. 30 shows an atlas frame according to embodiments.

FIG. 30 shows an atlas frame including tiles encoded by the encoder10002 of FIG. 1, the encoder of FIG. 4, the encoder of FIG. 15, thetransmission device of FIG. 18, the system of FIGS. 20 and 21, and thelike. The figure shows an atlas frame including tiles decoded by thedecoder 10008 of FIG. 1, the decoder of FIGS. 16 and 17, the receptiondevice of FIG. 19, the system of FIG. 23, and the like.

An atlas frame is divided into one or more tile rows and one or moretile columns. A tile is a rectangular region of an atlas frame. A tilegroup contains a plurality of tiles of an atlas frame. A tile and a tilegroup may not be distinguished from each other, and a tile group maycorrespond to one tile. Only rectangular tile groups are supported. Inthis mode, a tile group (or tile) may contain a plurality of tiles of anatlas frame that collectively form a rectangular region of the atlasframe. FIG. 30 shows an example tile group (or tile) partitioning of anatlas frame according to embodiments, where the atlas frame is dividedinto 24 tiles (6 tile columns and 4 tile rows) and 9 rectangular tilegroups. A tile group may be used as a term corresponding to a tilewithout distinction between a tile group and a tile according toembodiments.

That is, according to embodiments, the tile group 49000 may correspondto a tile 30010 and may be referred to as the tile 30010. In addition,the tile 30010 may correspond to a tile partition and may be referred toas a tile partition. The terms signaling information may also be changedto and referred.

FIG. 31 shows the structure of an atlas bitstream according toembodiments.

FIG. 31 shows an example in which the payload 26040 of the unit 26020 ofthe bitstream 26000 in FIG. 26 carries an atlas bitstream.

According to embodiments, the term “sub-” may be interpreted as meaninga part. According to embodiments, a sub-bitstream may be interpreted asa bitstream.

According to embodiments, an atlas bitstream may contain a sample streamNAL header and a sample stream NAL unit.

Each sample stream NAL unit according to the embodiments may include anatlas sequence parameter set (ASPS) (see FIG. 34), an atlas adaptationparameter set (AAPS) (see FIG. 37), an atlas frame parameter set (AFPS)(see FIG. 35), one or more atlas tile groups, one or more essentialSEIs, and one or more non-essential SEIs.

Referring to FIG. 31, the V-PCC unit payload of a V-PCC unit carrying anatlas sub-bitstream may be composed of one or more sample stream NALunits.

Hereinafter, syntax of information contained in the atlas bitstream ofFIG. 31 will be described.

FIG. 32 shows a sample stream NAL unit, a sample stream NAL unit header,a NAL unit, and a NAL unit header included in a bitstream containingpoint cloud data according to embodiments.

FIG. 32 shows the syntax of data contained in the atlas bitstream ofFIG. 31;

ssnh_unit_size_precision_bytes_minus1 plus 1 specifies the precision, inbytes, of the ssnu_nal_unit_size element in all sample stream NAL units.ssnh_unit_size_precision_bytes_minus1 may be in the range of 0 to 7.

ssnu_nal_unit_size specifies the size, in bytes, of the subsequent NALunit. The number of bits used to represent ssnu_nal_unit_size may beequal to

(ssnh_unit_size_precision_bytes_minus1+1)*8.

NumBytesInNalUnit indicates the size in bytes of a NAL unit.

NumBytesInRbsp indicates the number of bytes belonging to the payload ofthe NAL unit, and may be initialized to 0.

rbsp_byte[i] is the i-th byte of the RBSP. The RBSP may be expressed asan ordered sequence of bytes.

nal_forbidden_zero bit may be equal to zero (0).

nal_unit_type may have values as shown in FIG. 52. nal_unit_typespecifies the type of the RBSP data structure contained in the NAL unit.

nal_layer_id specifies the identifier of the layer to which an ACL NALunit belongs or the identifier of a layer to which a non-ACL NAL unitapplies.

nal_temporal_id_plus1 minus 1 specifies a temporal identifier for theNAL unit.

FIG. 33 shows NAL unit types according to embodiments.

FIG. 33 shows nal_unit_type included in the NAL unit header of thesample stream NAL unit of FIG. 31.

NAL TRAIL: A coded tile group of a non-TSA, non STSA trailing atlasframe may be included in the NAL unit. The RBSP syntax structure of theNAL unit is atlas_tile_group_layer_rbsp( ) or atlas_tile_layer_rbsp( ).The type class of the NAL unit is ACL. According to embodiments, a tilegroup may correspond to a tile.

NAL TSA: A coded tile group of a TSA atlas frame may be included in theNAL unit. The RBSP syntax structure of the NAL unit isatlas_tile_group_layer_rbsp( ) or atlas_tile_layer_rbsp( ). The typeclass of the NAL unit is ACL.

NAL_STSA: A coded tile group of an STSA atlas frame may be included inthe NAL unit. The RBSP syntax structure of the NAL unit isatlas_tile_group_layer_rbsp( ) or atlas_tile_layer_rbsp( ). The typeclass of the NAL unit is ACL.

NAL_RADL: A coded tile group of an RADL atlas frame may be included inthe NAL unit. The RBSP syntax structure of the NAL unit isatlas_tile_group_layer_rbsp( ) or atlas_tile_layer_rbsp( ). The typeclass of the NAL unit is ACL.

NAL_RASL: A coded tile group of an RASL atlas frame may be included inthe NAL unit. The RBSP syntax structure of the NAL unit isatlas_tile_group_layer_rbsp( ) or aatlas_tile_layer_rbsp( ). The typeclass of the NAL unit is ACL.

NAL_SKIP: A coded tile group of a skipped atlas frame may be included inthe NAL unit. The RBSP syntax structure of the NAL unit isatlas_tile_group_layer_rbsp( ) or atlas_tile_layer_rbsp( ). The typeclass of the NAL unit is ACL.

NAL_RSV_ACL_6 to NAL_RSV_ACL_9: Reserved non-IRAP ACL NAL unit types maybe included in the NAL unit. The type class of the NAL unit is ACL.

NAL_BLA_W_LP, NAL_BLA_W_RADL, NAL_BLA_N_LP: A coded tile group of a BLAatlas frame may be included in the NAL unit. The RBSP syntax structureof the NAL unit is atlas_tile_group_layer_rbsp( ) oratlas_tile_layer_rbsp( ). The type class of the NAL unit is ACL.

NAL_GBLA_W_LP, NAL_GBLA_W_RADL, NAL_GBLA_N_LP: A coded tile group of aGBLA atlas frame may be included in the NAL unit. The RBSP syntaxstructure of the NAL unit is atlas_tile_group_layer_rbsp( ) oratlas_tile_layer_rbsp( ). The type class of the NAL unit is ACL.

NAL_IDR_W_RADL, NAL_IDR_N_LP: A coded tile group of an IDR atlas framemay be included in the NAL unit. The RBSP syntax structure of the NALunit is atlas_tile_group_layer_rbsp( ) or atlas_tile_layer_rbsp( ). Thetype class of the NAL unit is ACL.

NAL_GIDR_W_RADL, NAL_GIDR_N_LP: A coded tile group of a GIDR atlas framemay be included in the NAL unit. The RBSP syntax structure of the NALunit is atlas_tile_group_layer_rbsp( ) or atlas_tile_layer_rbsp( ). Thetype class of the NAL unit is ACL.

NAL_CRA: A coded tile group of a CRA atlas frame may be included in theNAL unit. The RBSP syntax structure of the NAL unit isatlas_tile_group_layer_rbsp( ) or atlas_tile_layer_rbsp( ). The typeclass of the NAL unit is ACL.

NAL_GCRA: A coded tile group of a GCRA atlas frame may be included inthe NAL unit. The RBSP syntax structure of the NAL unit isatlas_tile_group_layer_rbsp( ) or atlas_tile_layer_rbsp( ). The typeclass of the NAL unit is ACL.

NAL_IRAP_ACL_22, NAL_IRAP_ACL_23: Reserved IRAP ACL NAL unit types maybe included in the NAL unit. The type class of the NAL unit is ACL.

NAL_RSV_ACL_24 to NAL_RSV_ACL_31: Reserved non-IRAP ACL NAL unit typesmay be included in the NAL unit. The type class of the NAL unit is ACL.

NAL ASPS: An atlas sequence parameter set may be included in the NALunit. The RBSP syntax structure of the NAL unit is atlassequence_parameter_set_rbsp( ). The type class of the NAL unit isnon-ACL.

NAL_AFPS: An atlas frame parameter set may be included in the NAL unit.The RBSP syntax structure of the NAL unit isatlas_frame_parameter_set_rbsp( ). The type class of the NAL unit isnon-ACL.

NAL_AUD: An access unit delimiter may be included in the NAL unit. TheRBSP syntax structure of the NAL unit is access_unit_delimiter_rbsp( ).The type class of the NAL unit is non-ACL.

NAL_VPCC_AUD: A V-PCC access unit delimiter may be included in the NALunit. The RBSP syntax structure of the NAL unit isaccess_unit_delimiter_rbsp( ). The type class of the NAL unit isnon-ACL.

NAL_EOS: The NAL unit type may be end of sequence. The RBSP syntaxstructure of the NAL unit is end_of_seq_rbsp( ). The type class of theNAL unit is non-ACL.

NAL_EOB: The NAL unit type may be end of bitstream. The RBSP syntaxstructure of the NAL unit is end of atlas_sub_bitstream_rbsp( ). Thetype class of the NAL unit is non-ACL.

NAL_FD_Filler: The NAL unit type may be filler_data_rbsp( ). The typeclass of the NAL unit is non-ACL.

NAL_PREFIX_NSEI, NAL_SUFFIX_NSEI: The NAL unit type may be non-essentialsupplemental enhancement information. The RBSP syntax structure of theNAL unit is sei_rbsp ( ). The type class of the NAL unit is non-ACL.

NAL_PREFIX_ESEI, NAL_SUFFIX_ESEI: The NAL unit type may be essentialsupplemental enhancement information. The RBSP syntax structure of theNAL unit is sei_rbsp ( ). The type class of the NAL unit is non-ACL.

NAL_AAPS: The NAL unit type may be atlas adaptation parameter set. TheRBSP syntax structure of the NAL unit isatlas_adaptation_parameter_set_rbsp( ). The type class of the NAL unitis non-ACL.

NAL_RSV_NACL_44 to NAL_RSV_NACL_47: The NAL unit type may be reservednon-ACL NAL unit types. The type class of the NAL unit is non-ACL.

NAL_UNSPEC_48 to NAL_UNSPEC_63: The NAL unit type may be unspecifiednon-ACL NAL unit types. The type class of the NAL unit is non-ACL.

FIG. 34 shows an atlas sequence parameter set according to embodiments.

FIG. 34 shows an atlas sequence parameter set (ASPS) contained in theatlas bitstream of FIG. 31.

Each sample stream NAL unit may contain one of an atlas parameter set,for example, ASPS, AAPS, or AFPS, information about one or more atlastile groups, and SEIs.

The ASPS may include syntax elements that apply to zero or more entirecoded atlas sequences (CASs) as determined by the content of a syntaxelement found in the ASPS referred to by a syntax element found in eachtile group header.

The ASPS may include the following elements.

asps_atlas_sequence_parameter_set_id may provide an identifier for theatlas sequence parameter set for reference by other syntax elements.

asps_frame_width indicates the atlas frame width in terms of integernumber of samples, where a sample corresponds to a luma sample of avideo component.

asps_frame_height indicates the atlas frame height in terms of integernumber of samples, where a sample corresponds to a luma sample of avideo component.

asps_log 2_patch_packing_block_size specifies the value of the variablePatchPackingBlockSize that is used for the horizontal and verticalplacement of the patches within the atlas.

asps_log 2_max_atlas_frame_order_cnt_lsb_minus4 specifies the value ofthe variable MaxAtlasFrmOrderCntLsb that is used in the decoding processfor the atlas frame order count.

asps_max_dec_atlas_frame_buffering_minus1 plus 1 specifies the maximumrequired size of the decoded atlas frame buffer for the CAS in units ofatlas frame storage buffers.

asps_long_term_ref_atlas_frames_flag equal to 0 specifies that no longterm reference atlas frame is used for inter prediction of any codedatlas frame in the CAS. asps_long_term_ref_atlas_frames_flag equal to 1specifies that long term reference atlas frames may be used for interprediction of one or more coded atlas frames in the CAS.

asps_num_ref_atlas_frame_lists in asps specifies the number of theref_list_struct(rlsIdx) syntax structures included in the atlas sequenceparameter set.

ref_list_struct(i) as many as asps_num_ref_atlas_frame_lists in asps maybe included in the atlas sequence parameter set.

asps use eight orientations flag equal to 0 specifies that the patchorientation index for a patch with index j in a frame with index i,pdu_orientation_index[i][j], is in the range of 0 to 1, inclusive. aspsuse eight orientations flag equal to 1 specifies that the patchorientation index for a patch with index j in a frame with index i,pdu_orientation_index[i][j], is in the range of 0 to 7, inclusive.

asps_extended_projection_enabled_flag equal to 0 specifies that thepatch projection information is not signaled for the current atlas tilegroup. asps_extended_projection_enabled_flag equal to 1 specifies thatthe patch projection information is signaled for the current atlas tilegroup or the current atlas tile.

asps_normal_axis_limits_quantization_enabled_flag equal to 1 specifiesthat quantization parameters shall be signalled and used for quantizingthe normal axis related elements of a patch data unit, a merge patchdata unit, or an inter patch data unit. Ifasps_normal_axis_limits_quantization_enabled_flag is equal to 0, then noquantization is applied on any normal axis related elements of a patchdata unit, a merge patch data unit, or an inter patch data unit.

asps_normal_axis_max_delta_value_enabled_flag equal to 1 specifies thatthe maximum nominal shift value of the normal axis that may be presentin the geometry information of a patch with index i in a frame withindex j will be indicated in the bitstream for each patch data unit, amerge patch data unit, or an inter patch data unit. Ifasps_normal_axis_max_delta_value_enabled_flag is equal to 0, then themaximum nominal shift value of the normal axis that may be present inthe geometry information of a patch with index i in a frame with index jshall not be indicated in the bitstream for each patch data unit, amerge patch data unit, or an inter patch data unit.

asps_remove_duplicate_point_enabled_flag equal to 1 indicates thatduplicated points are not constructed for the current atlas, where aduplicated point is a point with the same 2D and 3D geometry coordinatesas another point from a lower index map.asps_remove_duplicate_point_enabled_flag equal to 0 indicates that allpoints are reconstructed.

asps_max_dec_atlas_frame_buffering_minus1 plus 1 specifies the maximumrequired size of the decoded atlas frame buffer for the CAS in units ofatlas frame storage buffers.

asps_pixel_deinterleaving_flag equal to 1 indicates that the decodedgeometry and attribute videos for the current atlas contain spatiallyinterleaved pixels from two maps. asps_pixel_deinterleaving_flag equalto 0 indicates that the decoded geometry and attribute videoscorresponding to the current atlas contain pixels from only a singlemap.

asps_patch_precedence_order_flag equal to 1 indicates that patchprecedence for the current atlas is the same as the decoding order.asps_patch_precedence_order_flag equal to 0 indicates that patchprecedence for the current atlas is the reverse of the decoding order.

asps_patch_size_quantizer_present_flag equal to 1 indicates that thepatch size quantization parameters are present in an atlas tile groupheader. asps_patch_size_quantizer_present_flag equal to 0 indicates thatthe patch size quantization parameters are not present.

asps_eom_patch_enabled_flag equal to 1 indicates that the decodedoccupancy map video for the current atlas contains information relatedto whether intermediate depth positions between two depth maps areoccupied. asps_eom_patch_enabled_flag equal to 0 indicates that thedecoded occupancy map video does not contain information related towhether intermediate depth positions between two depth maps areoccupied.

asps_point_local_reconstruction_enabled_flag equal to 1 indicates thatpoint local reconstruction mode information may be present in thebitstream for the current atlas.asps_point_local_reconstruction_enabled_flag equal to 0 indicates thatno information related to the point local reconstruction mode is presentin the bitstream for the current atlas).

asps_map_count_minus1 plus 1 indicates the number of maps that may beused for encoding the geometry and attribute data for the current atlas.

asps_pixel_deinterleaving_map_flag[i] equal to 1 indicates that decodedgeometry and attribute videos corresponding to map with index i in thecurrent atlas contain spatially interleaved pixels corresponding to twomaps. asps_pixel_deinterleaving_map_flag[i] equal to 0 indicates thatdecoded geometry and attribute videos corresponding to map index i inthe current atlas contain pixels corresponding to a single map.

asps_eom_fix_bit_count_minus1 plus 1 indicates the size in bits of theEOM codeword.

asps_surface_thickness_minus1 plus 1 specifies the maximum absolutedifference between an explicitly coded depth value and interpolateddepth value when asps_pixel__deinterleaving_enabled_flag orasps_point_local_reconstruction_enabled_flag is equal to 1.

asps_vui_parameters_present_flag equal to 1 specifies that thevui_parameters( ) syntax structure is present.asps_vui_parameters_present_flag equal to 0 specifies that thevui_parameters( ) syntax structure is not present.

asps_extension_flag equal to 0 specifies that noasps_extension_data_flag syntax elements are present in the ASPS RBSPsyntax structure.

asps_extension_data_flag may have any value.

rbsp_trailing_bits is used for the purpose of filling the remaining bitswith 0 for byte alignment after adding a stop bit of 1 to indicate theend of RBSP data.

FIG. 35 shows an atlas frame parameter set according to embodiments.

FIG. 35 shows a detailed syntax of an atlas frame parameter setcontained in the atlas bitstream of shows 31.

The atlas frame parameter set (AFPS) includes a syntax structureincluding syntax elements that apply to zero or more entire coded atlasframes.

afps_atlas_frame_parameter_set_id identifies the atlas frame parameterset for reference by other syntax elements.

afps_atlas_sequence_parameter_set_id specifies the value ofasps_atlas_sequence_parameter_set_id for the active atlas sequenceparameter set.

atlas_frame_tile_information( ) will be described with reference to FIG.36.

afps_output_flag_present_flag equal to 1 indicates that theatgh_frame_output_flag syntax element is present in the associated tilegroup headers. afps_output_flag_present_flag equal to 0 indicates thatthe atgh_frame_output_flag syntax element is not present in theassociated tile group headers.

afps_num_ref_idx_default_active_minus1 plus 1 specifies the inferredvalue of the variable NumRefIdxActive for the tile group or tile withatgh_num_ref_idx_active_override_flag equal to 0.

afps_additional_lt_afoc_lsb_len specifies the value of the variableMaxLtAtlasFrmOrderCntLsb that is used in the decoding process forreference atlas frame.

afps_3d_pos_x_bit_count_minus1 plus 1 specifies the number of bits inthe fixed-length representation of pdu_3d_pos_x[j] of patch with index jin an atlas tile group that refers to afps_atlas_frame_parameter_set_id.

afps_3d_pos_y_bit_count_minus1 plus 1 specifies the number of bits inthe fixed-length representation of pdu_3d_pos_y[j] of patch with index jin an atlas tile group that refers to afps_atlas_frame_parameter_set_id.

afps_lod_mode_enabled_flag equal to 1 indicates that the LOD parametersmay be present in a patch. afps_lod_mode_enabled_flag equal to 0indicates that the LOD parameters are not present in a patch.

afps_override_eom_for_depth_flag equal to 1 indicates that the values ofafps_eom_number_of_patch_bit_count_minus1 andafps_eom_max_bit_count_minus1 are explicitly present in the bitstream.afps_override_eom_for_depth_flag equal to 0 indicates that the values ofafps_eom_number_of_patch_bit_count_minus1 andafps_eom_max_bit_count_minus1 are implicitly derived.

afps_eom_number_of_patch_bit_count_minus1 plus 1 specifies the number ofbits used to represent the number of geometry patches associated in anEOM attribute patch in an atlas frame that is associated with this atlasframe parameter set.

afps_eom_max_bit_count_minus1 plus 1 specifies the number of bits usedto represent the number of EOM points per geometry patch associated withan EOM attribute patch in an atlas frame that is associated with thisatlas frame parameter set.

afps_raw_3d_pos_bit_count_explicit_mode_flag equal to 1 indicates thatthe number of bits in the fixed-length representation of rpdu_3d_pos_x,rpdu_3d_pos_y, and rpdu_3d_pos_z is explicitly coded byatgh_raw_3d_pos_axis_bit_count_minus1 in the atlas tile group headerthat refers to afps_atlas_frame_parameter_set_id.afps_raw_3d_pos_bit_count_explicit_mode_flag equal to 0 indicates thevalue of atgh_raw_3d_pos_axis_bit_count_minus1 is implicitly derived.

afps_extension_flag equal to 0 specifies that noafps_extension_data_flag syntax elements are present in the AFPS RBSPsyntax structure.

afps_extension_data_flag may contain extension related data.

FIG. 36 shows atlas_frame_tile_information according to embodiments.

FIG. 36 shows a syntax of atlas frame tile information included in theatlas bitstream of FIG. 31.

afti_single_tile_in_atlas_frame_flag equal to 1 specifies that there isonly one tile in each atlas frame referring to the AFPS.afti_single_tile_in_atlas_frame_flag equal to 0 specifies that there ismore than one tile in each atlas frame referring to the AFPS.

afti_uniform_tile_spacing_flag equal to 1 specifies that tile column androw boundaries are distributed uniformly across the atlas frame andsignaled using the syntax elements, afti_tile_cols_width_minus1 andafti_tile_rows_height_minus1, respectively.afti_uniform_tile_spacing_flag equal to 0 specifies that tile column androw boundaries may or may not be distributed uniformly across the atlasframe and are signaled using the syntax elementsafti_num_tile_columns_minus1 and afti_num_tile_rows_minus1 and a list ofsyntax element pairs afti_tile_column_width_minus1[i] andafti_tile_row_height_minus1[i].

afti_tile_cols_width_minus1 plus 1 specifies the width of the tilecolumns excluding the right-most tile column of the atlas frame in unitsof 64 samples when afti_uniform_tile_spacing_flag is equal to 1.

afti_tile_rows_height_minus1 plus 1 specifies the height of the tilerows excluding the bottom tile row of the atlas frame in units of 64samples when afti_uniform_tile_spacing_flag is equal to 1.

When afti_uniform_tile_spacing_flag is not equal to 1, the followingelements are included in the atlas frame tile information.

afti_num_tile_columns_minus1 plus 1 specifies the number of tile columnspartitioning the atlas frame when afti_uniform_tile_spacing_flag isequal to 0.

afti_num_tile_rows_minus1 plus 1 specifies the number of tile rowspartitioning the atlas frame when pti_uniform_tile_spacing_flag is equalto 0.

afti_tile_column_width_minus1[i] plus 1 specifies the width of the i-thtile column in units of 64 samples.

afti_tile_column_width_minus1[i] is included in the atlas frame tileinformation according to the value of afti_num_tile_columns_minus1.

afti_tile_row_height_minus1 [i] plus 1 specifies the height of the i-thtile row in units of 64 samples.

afti_tile_row_height_minus1 [i] is included in the atlas frame tileinformation according to the value of afti_num_tile_rows_minus1.

afti_single_tile_per_tile_group_flag equal to 1 specifies that each tilegroup (or tile) that refers to this AFPS includes one tile.afti_single_tile_per_tile_group_flag equal to 0 specifies that a tilegroup that refers to this AFPS may include more than one tile. When notpresent, the value of afti_single_tile_per_tile_group_flag may beinferred to be equal to 1.

Based on the value of afti_num_tile_groups_in_atlas_frame_minus1,afti_tile_idx[i] is included in the atlas frame tile information.

When afti_single_tileper_tile_group_flag is equal to 0,afti_num_tile_groups_in_atlas_frame_minus1 is carried in the atlas frametile information.

afti_num_tile_groups_in_atlas_frame_minus1 plus 1 specifies the numberof tile groups in each atlas frame referring to the AFPS. The value ofafti_num_tile_groups_in_atlas_frame_minus1 may be in the range of 0 toNumTilesInAtlasFrame−1, inclusive. When not present andafti_single_tileper_tile_group_flag is equal to 1, the value ofafti_num_tile_groups_in_atlas_frame_minus1 may be inferred to be equalto NumTilesInAtlasFrame−1.

The following elements are included in the atlas frame tile informationaccording to the value of as much asafti_num_tile_groups_in_atlas_frame_minus1.

afti_top_left_tile_idx[i] specifies the tile index of the tile locatedat the top-left corner of the i-th tile group (tile). The value ofafti_top_left_tile_idx[i] is not equal to the value ofafti_top_left_tile_idx[j] for any i not equal to j. When not present,the value of afti_top_left_tile_idx[i] may be inferred to be equal to i.The length of the afti_top_left_tile_idx[i] syntax element may beCeil(Log 2(NumTilesInAtlasFrame) bits.

afti_bottom_right_tile_idx_delta[i] specifies the difference between thetile index of the tile located at the bottom-right corner of the i-thtile group (tile) and afti_top_left_tile_idx[i]. Whenafti_single_tileper_tile_group_flag is equal to 1, the value ofafti_bottom_right_tile_idx_delta[i] is inferred to be equal to 0. Thelength of the afti_bottom_right_tile_idx_delta[i] syntax element isCeil(Log 2(NumTilesInAtlasFrame−afti_top_left_tile_idx[i])) bits.

afti_signalled_tile_group_id_flag equal to 1 specifies that the tilegroup ID for each tile group is signaled.

When afti_signalled_tile_group_id_flag is equal to 1,afti_signalled_tile_group_id_length_minus1 and afti_tile_group_id[i] maybe carried in the atlas frame tile information. When the value of thisflag is 0, tile group IDs may not be signaled.

afti_signalled_tile_group_id_length_minus1 plus 1 specifies the numberof bits used to represent the syntax element afti_tile_group_id[i] whenpresent, and the syntax element atgh_address in tile group headers.

afti_tile_group_id[i] specifies the tile group ID of the i-th tilegroup. The length of the afti_tile_group_id[i] syntax element isafti_signalled_tile_group_id_length_minus1+1 bits.

afti_tile_group_id[i] is included in the atlas frame tile informationaccording to the value of afti_num_tile_groups_in_atlas_frame_minus1.

FIG. 37 shows atlas_adaptation_parameter_set according to embodiments.

FIG. 37 shows an atlas adaptation parameter set included in the atlasbitstream of FIG. 31.

An AAPS RBSP includes parameters that may be referred to by the codedtile group NAL units of one or more coded atlas frames. At most one AAPSRBSP is considered active at any given moment during the operation ofthe decoding process. Activation of any particular AAPS RBSP results indeactivation of the previously active AAPS RBSP.

aaps_atlas_adaptation_parameter_set_id_may identify the atlas adaptationparameter set for reference by other syntax elements.

aaps_atlas_sequence_parameter_set_id specifies the value ofasps_atlas_sequence_parameter_set_id for the active atlas sequenceparameter set.

aaps_camera_parameters_present_flag equal to 1 specifies that cameraparameters are present in the current atlas adaptation parameter set.aaps_camera_parameters_present_flag equal to 0 specifies that cameraparameters for the current adaptation parameter set are not be present.

aaps_extension_flag equal to 0 specifies that noaaps_extension_data_flag syntax elements are present in the AAPS RBSPsyntax structure.

aaps_extension_data_flag may have various values.

FIG. 38 shows atlas_camera_parameters according to embodiments.

FIG. 38 shows atlas_camera_parameters included in FIG. 37.

acp_camera_model indicates the camera model for point cloud frames thatare associated with the current adaptation parameter set.

When acp_camera_model is equal to 0, the name of acp_camera_model is notspecified.

When acp_camera_model is equal to 1 acp_camera_model indicates anorthographic camera model.

When acp_camera_model has a value from 2 to 255, acp_camera_model may bereserved for future use.

acp_scale_enabled_flag equal to 1 indicates that scale parameters forthe current camera model are present. acp_scale_enabled_flag equal to 0indicates that scale parameters for the current camera model are notpresent.

acp_offset_enabled_flag equal to 1 indicates that offset parameters forthe current camera model are present. acp_offset_enabled_flag equal to 0indicates that offset parameters for the current camera model are notpresent.

acp_rotation_enabled_flag equal to 1 indicates that rotation parametersfor the current camera model are present. acp_rotation_enabled_flagequal to 0 indicates that rotation parameters for the current cameramodel are not present.

acp_scale_on_axis[d] specifies the value of the scale [d], along the daxis for the current camera model. The value of d is in the range of 0to 2, inclusive, with the values of 0, 1, and 2 corresponding to the X,Y, and Z axes, respectively.

acp_offset_on_axis[d] indicates the value of the offset along the d axisfor the current camera model where d is in the range of 0 to 2,inclusive. The values of d equal to 0, 1, and 2 may correspond to the X,Y, and Z axis, respectively.

acp_rotation_qx specifies the x component, qX, for the rotation of thecurrent camera model using the quaternion representation.

acp_rotation_qy specifies the y component, qY, for the rotation of thecurrent camera model using the quaternion representation.

acp_rotation_qz specifies the z component, qZ, for the rotation of thecurrent camera model using the quaternion representation.

FIG. 39 shows atlas tile_group_layer and atlas_tile_group_headeraccording to embodiments.

FIG. 39 shows an atlas tile group layer and an atlas tile group headerincluded in the atlas bitstream of FIG. 31.

atgh_atlas_frame_parameter_set_id specifies the value ofafps_atlas_frame_parameter_set_id for the active atlas frame parameterset for the current atlas tile group.

atgh_atlas_adaptation_parameter_set_id specifies the value ofaaps_atlas_adaptation_parameter_set_id_for the active atlas adaptationparameter set for the current atlas tile group.

atgh_address specifies the tile group address of the tile group. Whennot present, the value of atgh_address is inferred to be equal to 0. Thetile group address is the tile group ID of the tile group. The length ofatgh_address may be afti_signalled_tile_group_id_length_minus1+1 bits.When afti_signalled_tile_group_id_flag is equal to 0, the value ofatgh_address is in the range of 0 toafti_num_tile_groups_in_atlas_frame_minus1, inclusive. On the otherhand, the value of atgh_address may be in the range of 0 to2(afti_signalled_tile_group_id_length_minus1+1)−1, inclusive.

atgh_type specifies the coding type of the current atlas tile group.

When atgh_type is equal to 0, the type is inter atlas tile group(P_TILE_GRP).

When atgh_type is equal to 1, the type is intra atlas tile group(I_TILE_GRP).

When atgh_type is equal to 2, the type is SKIP atlas tile group(SKIP_TILE_GRP).

When atgh_type is equal to 3, the type is RESERVED.

atgh_atlas_output_flag may affects the decoded atlas output and removalprocesses

atgh_atlas_frm_order_cnt_lsb specifies the atlas frame order countmodulo MaxAtlasFrmOrderCntLsb for the current atlas tile group.

atgh_ref_atlas_frame_list_sps_flag equal to 1 specifies that thereference atlas frame list of the current atlas tile group may bederived based on one of the ref_list_struct(rlsIdx) syntax structures inthe active ASPS. atgh_ref_atlas_frame_list_sps_flag equal to 0 specifiesthat the reference atlas frame list of the current atlas tile group maybe derived based on the ref_list_struct(rlsIdx) syntax structuredirectly included in the tile group header of the current atlas tilegroup.

atgh_ref_atlas_frame_list_idx specifies the index for the list of theref_list_struct(rlsIdx) syntax structures included in the active ASPS ofthe ref_list_struct(rlsIdx) syntax structure that is used for derivationof the reference atlas frame list for the current atlas tile group.

atgh_additional_afoc_lsb_present_flag[j] equal to 1 specifies thatatgh_additional_afoc_lsb_val[j] is present for the current atlas tilegroup. atgh_additional_afoc_lsb_present_flag[j] equal to 0 specifiesthat atgh_additional_afoc_lsb_val[j] is not present.

atgh_additional_afoc_lsb_val[j] specifies the value ofFullAtlasFrmOrderCntLsbLt[RlsIdx][j] for the current atlas tile group.

atgh_pos_min_z_quantizer specifies the quantizer that is to be appliedto the pdu_3d_pos_min_z[p] value of the patch p. Ifatgh_pos_min_z_quantizer is not present, its value is inferred to beequal to 0.

atgh_pos_delta_max_z_quantizer specifies the quantizer that is to beapplied to the pdu_3d_pos_delta_max_z[p] value of the patch with indexp. When atgh_pos_delta_max_z_quantizer is not present, the value thereofmay be inferred to be equal to 0.

atgh_patch_size_x_info_quantizer specifies the value of the quantizerPatchSizeXQuantizer that is to be applied to the variablespdu_2d_size_x_minus1[p], mpdu_2d_delta_size_x[p],ipdu_2d_delta_size_x[p], rpdu_2d_size_x_minus1 [p], andepdu_2d_size_x_minus1 [p] of a patch with index p. Whenatgh_patch_size_x_info_quantizer is not present, the value thereof maybe inferred to be equal to asps_log 2_patch_packing_block_size.

atgh_patch_size_y_info_quantizer specifies the value of the quantizerPatchSizeYQuantizer that is to be applied to the variablespdu_2d_size_y_minus1[p], mpdu_2d_delta_size_y[p],ipdu_2d_delta_size_y[p], rpdu_2d_size_y_minus1 [p], andepdu_2d_size_y_minus1[p] of a patch with index p. Whenatgh_patch_size_y_info_quantizer is not present, the value thereof maybe inferred to be equal to asps_log 2_patch_packing_block_size.

atgh_raw_3d_pos_axis_bit_count_minus1 plus 1 specifies the number ofbits in the fixed-length representation of rpdu_3d_pos_x, rpdu_3d_pos_y,and rpdu_3d_pos_z.

atgh_num_ref_idx_active_override_flag equal to 1 specifies that thesyntax element atgh_num_ref_idx_active_minus1 is present for the currentatlas tile group. atgh_num_ref_idx_active_override_flag equal to 0specifies that the syntax element atgh_num_ref_idx_active_minus1 is notpresent. When atgh_num_ref_idx_active_override_flag is not present, thevalue thereof may be inferred to be equal to 0.

atgh_num_ref_idx_active_minus1 specifies the maximum reference index forreferencing the atlas frame list that may be used to decode the currentatlas tile group. When the value of NumRefIdxActive is equal to 0, noreference index for the reference atlas frame list may be used to decodethe current atlas tile group.

byte_alignment is used for the purpose of filling the remaining bitswith 0 for byte alignment after adding 1 as a stop bit to indicate theend of data.

FIG. 40 shows a reference list structure (ref_list_struct) according toembodiments.

FIG. 40 shows the reference list structure included in FIG. 39.

num_ref_entries[rlsIdx] specifies the number of entries in theref_list_struct(rlsIdx) syntax structure.

st_ref_atlas_frame_flag[rlsIdx][i] equal to 1 specifies that the i-thentry in the ref_list_struct(rlsIdx) syntax structure is a short termreference atlas frame entry. st_ref_atlas_frame_flag[rlsIdx][i] equal to0 specifies that the i-th entry in the ref_list_struct(rlsIdx) syntaxstructure is a long term reference atlas frame entry. When not present,the value of st_ref_atlas_frame_flag[rlsIdx][i] may be inferred to beequal to 1.

abs_delta_afoc_st[rlsIdx][i] specifies, when the i-th entry is the firstshort term reference atlas frame entry in ref_list_struct(rlsIdx) syntaxstructure, the absolute difference between the atlas frame order countvalues of the current atlas tile group and the atlas frame referred toby the i-th entry, or specifies, when the i-th entry is a short termreference atlas frame entry but not the first short term reference atlasframe entry in the ref_list_struct(rlsIdx) syntax structure, theabsolute difference between the atlas frame order count values of theatlas frames referred to by the i-th entry and by the previous shortterm reference atlas frame entry in the ref_list_struct(rlsIdx) syntaxstructure.

strpf_entry_sign_flag[rlsIdx][i] equal to 1 specifies that i-th entry inthe syntax structure ref_list_struct(rlsIdx) has a value greater than orequal to 0. strpf_entry_sign_flag[rlsIdx][i] equal to 0 specifies thatthe i-th entry in the syntax structure ref_list_struct(rlsIdx) has avalue less than 0. When not present, the value ofstrpf_entry_sign_flag[rlsIdx][i] may be inferred to be equal to 1.

afoc_lsb_lt[rlsIdx][i] specifies the value of the atlas frame ordercount modulo MaxAtlasFrmOrderCntLsb of the atlas frame referred to bythe i-th entry in the ref_list_struct(rlsIdx) syntax structure. Thelength of the afoc_lsb_lt[rlsIdx][i] syntax element may be asps_log2_max_atlas_frame_order_cnt_lsb_minus4+4 bits.

FIG. 41 shows atlas tile group data (atlas_tile_group_data_unit)according to embodiments.

FIG. 41 shows atlas tile group data included in the atlas bitstream ofFIG. 31.

atgdu_patch_mode[p] indicates the patch mode for the patch with index pin the current atlas tile group. A tile group withatgh_type=SKIP_TILE_GRP implies that the entire tile group informationis copied directly from the tile group with the same atgh_address asthat of the current tile group that corresponds to the first referenceatlas frame.

Patch mode types for I_TILE_GRP type atlas tile groups may be specifiedas follows.

atgdu_patch_mode equal to 0 indicates the non-predicted patch mode withthe identifier of I_INTRA.

atgdu_patch_mode equal to 1 indicates the RAW point patch mode with theidentifier of I_RAW.

atgdu_patch_mode equal to 2 indicates the EOM point patch mode with theidentifier of I_EOM.

The values of atgdu_patch_mode equal from 3 to 13 indicate reservedmodes with the identifier of I_RESERVED.

atgdu_patch_mode equal to 14 indicates the patch termination mode withthe identifier of I_END.

Patch mode types for the P TILE GRP type atlas tile groups may bespecified as follows.

atgdu_patch_mode equal to 0 indicates the patch skip mode with theidentifier of P_SKIP.

atgdu_patch_mode equal to 1 indicates the patch merge mode with theidentifier of P_MERGE.

atgdu_patch_mode equal to 2 indicates the inter predicted patch modewith the identifier of P_INTER.

atgdu_patch_mode equal to 3 indicates the non-predicted patch mode withthe identifier of P_INTRA.

atgdu_patch_mode equal to 4 indicates the RAW point patch mode with theidentifier of P_RAW.

atgdu_patch_mode equal to 5 indicates the EOM point patch mode with theidentifier of P_EOM.

The values of atgdu_patch_mode equal from 6 to 13 indicate reservedmodes with the identifier of P_RESERVED.

atgdu_patch_mode equal to 14 indicates the patch termination mode withthe identifier of P_END.

Patch mode types for SKIP_TILE_GRP type atlas tile groups may bespecified as follows.

atgdu_patch_mode equal to 0 indicates the patch skip mode with theidentifier of P SKIP.

FIG. 42 shows patch_information_data according to embodiments

FIG. 42 shows patch_information_data that may be included in FIG. 41.

The patch_information_data may carry the following information accordingto patchIdx and patchMode.

When atgh_type is SKIP_TILE_GR, skip_patch_data_unit(patchIdx) may becarried.

When atgh_type is P_TILE_GR, the following elements may be carried.Specifically, when patchMode is P_SKIP, skip_patch_data_unit(patchIdx)may be provided. When patchMode is P_MERGE,merge_patch_data_unit(patchIdx)) may be provided. When patchMode isP_INTRA, patch_data_unit(patchIdx) may be carried. When patchMode isP_INTER, inter_patch_data_unit(patchIdx) may be carried. When patchModeis P_RAW, raw_patch_data_unit(patchIdx) may be carried. When patchModeis P_EOM, eom_patch_data_unit(patchIdx) may be carried.

When atgh_type is I_TILE_GR, the following elements may be carried.Specifically, when patchMode is I_INTRA, patch_data_unit (patchIdx)) maybe carried. When patchMode is I_RAW, raw_patch_data_unit (patchIdx) maybe carried. When patchMode is I_EOM, eom_patch_data_unit(patchIdx) maybe carried.

FIG. 43 shows patch_data_unit according to embodiments.

FIG. 43 shows detailed information of the patch data unit included inFIG. 42;

pdu_2d_pos_x[p] specifies the x-coordinate (or left offset) of thetop-left corner of the patch bounding box for patch p in the currentatlas tile group, tileGroupIdx, expressed as a multiple ofPatchPackingBlockSize.

pdu_2d_pos_y[p] specifies the y-coordinate (or top offset) of thetop-left corner of the patch bounding box for patch p in the currentatlas tile group, tileGroupIdx, expressed as a multiple ofPatchPackingBlockSize.

pdu_2d_size_x_minus1 [p] plus 1 specifies the quantized width value ofthe patch with index p in the current atlas tile group, tileGroupIdx.

pdu_2d_size_y_minus1 [p] plus 1 specifies the quantized height value ofthe patch with index p in the current atlas tile group, tileGroupIdx.

pdu_3d_pos_x[p] specifies the shift to be applied to the reconstructedpatch points in the patch with index p of the current atlas tile groupalong the tangent axis.

pdu_3d_pos_y[p] specifies the shift to be applied to the reconstructedpatch points in the patch with index p of the current atlas tile groupalong the bitangent axis.

pdu_3d_pos_min_z[p] specifies the shift to be applied to thereconstructed patch points in the patch with index p of the currentatlas tile group along the normal axis.

pdu_3d_pos_delta_max_z[p], if present, specifies the nominal maximumvalue of the shift expected to be present in the reconstructed bitdepthpatch geometry samples, after conversion to their nominalrepresentation, in the patch with index p of the current atlas tilegroup along the normal axis.

pdu_projection_id[p] specifies the values of the projection mode and ofthe index of the normal to the projection plane for the patch with indexp of the current atlas tile group.

pdu_orientation_index[p] indicates the patch orientation index for thepatch with index p of the current atlas tile group.

x Identifier Rotation (x) Offset (x) 0 FPO_NULL $\quad\begin{bmatrix}1 & 0 \\0 & 1\end{bmatrix}$ $\quad\begin{bmatrix}0 \\0\end{bmatrix}$ 1 FPO_SWAP $\quad\begin{bmatrix}0 & 1 \\1 & 0\end{bmatrix}$ $\quad\begin{bmatrix}0 \\0\end{bmatrix}$ 2 FPO_ROT90 $\quad\begin{bmatrix}0 & {- 1} \\1 & 0\end{bmatrix}$ $\quad\begin{bmatrix}{{{Patch}\; 2{{d{Size}Y}\lbrack p\rbrack}} - 1} \\0\end{bmatrix}$ 3 FPO_ROT180 $\quad\begin{bmatrix}{- 1} & 0 \\0 & {- 1}\end{bmatrix}$ $\quad\begin{bmatrix}{{{Patch}\; 2{{d{Size}X}\lbrack p\rbrack}} - 1} \\{{{Patch}\; 2{{d{Size}Y}\lbrack p\rbrack}} - 1}\end{bmatrix}$ 4 FPO_ROT270 $\quad\begin{bmatrix}0 & 1 \\{- 1} & 0\end{bmatrix}$ $\quad\begin{bmatrix}0 \\{{{Patch}\; 2{{d{Size}X}\lbrack p\rbrack}} - 1}\end{bmatrix}$ 5 FPO_MIRROR $\quad\begin{bmatrix}{- 1} & 0 \\0 & 1\end{bmatrix}$ $\quad\begin{bmatrix}{{{Patch}\; 2{{d{Size}X}\lbrack p\rbrack}} - 1} \\0\end{bmatrix}$ 6 FPO_MROT90 $\quad\begin{bmatrix}0 & {- 1} \\{- 1} & 0\end{bmatrix}$ $\quad\begin{bmatrix}{{{Patch}\; 2{{d{Size}Y}\lbrack p\rbrack}} - 1} \\{{{Patch}\; 2{{d{Size}X}\lbrack p\rbrack}} - 1}\end{bmatrix}$ 7 FPO_MROT180 $\quad\begin{bmatrix}1 & 0 \\0 & {- 1}\end{bmatrix}$ $\quad\begin{bmatrix}0 \\{{{Patch}\; 2{{d{Size}Y}\lbrack p\rbrack}} - 1}\end{bmatrix}$

pdu_lod_enabled_flag[p] equal to 1 specifies that the LOD parameters arepresent for the current patch p. When pdu_lod_enabled_flag[p] is equalto 0, no LOD parameters are present for the current patch.

pdu_lod_scale_x_minus1 [p] specifies the LOD scaling factor to beapplied to the local x coordinate of a point in the patch with index pof the current atlas tile group, prior to its addition to the patchcoordinate Patch3dPosX[p].

pdu_lod_scale_y[p] specifies the LOD scaling factor to be applied to thelocal y coordinate of a point in the patch with index p of the currentatlas tile group, prior to its addition to the patch coordinatePatch3dPosY[p].

point_local_reconstruction_data(patchIdx) may include information forenabling the decoder to reconstruct points that are missing due tocompression loss or the like.

SEI messages assist in processes related to decoding, reconstruction,display, or other purposes. According to embodiments, there may be twotypes of SEI messages: essential and non-essential.

Non-essential SEI messages are not required by the decoding process.Conforming decoders are not required to process this information foroutput order conformance.

Essential SEI messages are an integral part of the V-PCC bitstream andshould not be removed from the bitstream. The essential SEI messages maybe categorized into two types:

Type-A essential SEI messages: These SEIs contain information requiredto check bitstream conformance and for output timing decoderconformance. Every V-PCC decoder conforming to point A should notdiscard any relevant Type-A essential SEI messages and consider the samefor bitstream conformance and for output timing decoder conformance.

Type-B essential SEI messages: V-PCC decoders that intend to conform toa particular reconstruction profile may not discard any relevant Type-Bessential SEI messages and may consider the same for the purposes of 3Dpoint cloud reconstruction and conformance.

Video-based point cloud compression represents volumetric encoding ofpoint cloud visual information. A V-PCC bitstream containing a codedpoint cloud sequence (CPCS) may be composed of VPCC units carrying aV-PCC parameter set (VPS), a coded atlas bitstream, a 2D video encodedoccupancy map bitstream, a 2D video encoded geometry bitstream, and zeroor more 2D video encoded attribute bitstreams.

The method/device according to the embodiments may receive the V-PCCbitstreams of FIGS. 25 and 26 through the file/segment encapsulator(20004 in FIG. 20, 21009 in FIG. 21). When a file (FIGS. 70 to 72) orpoint cloud data is an image, the method/device may encapsulate anddeliver the following information based on the container structure ofitems (FIG. 47).

When the file (FIGS. 70 to 72) or point cloud data is an image, themethod/device according to the embodiments may receive and decapsulatethe items (FIG. 47) through the file/segment decapsulator (20005 in FIG.20, 22000 in FIG. 22).

Volumetric Visual Track

A volumetric visual track may be identified by the volumetric visualmedia handler type ‘volv’ in the HandlerBox of the MediaBox.

Volumetric Visual Media Header

Box Type: ‘vvhd’

Container: MediaInformationBox

Mandatory: Yes

Quantity: Exactly one

Volumetric visual tracks use VolumetricVisualMediaHeaderBox in theMediaInformationBox.

aligned(8) class VolumetricVisualMediaHeaderBox extends FullBox(‘vvhd’,version = 0, 1) { }

“version” is an integer that specifies the version of this box.

Volumetric Visual Sample Entry

Volumetric visual tracks shall use a VolumetricVisualSampleEntry.

class VolumetricVisualSampleEntry(codingname) extends SampleEntry(codingname){ unsigned int(8)[32] compressor_name; }

compressor name is a name, for informative purposes. It is formatted ina fixed 32-byte field, with the first byte set to the number of bytes tobe displayed, followed by the number of bytes of displayable dataencoded using UTF-8, and then padding to complete 32 bytes total(including the size byte). The field may be set to 0.

Volumetric Visual Samples

The format of a volumetric visual sample is defined by the codingsystem.

Hereinafter, detailed information on a common data structure included ina volumetric visual track according to the V-PCC system will bedescribed.

V-PCC Unit Header Box

This box may be present in the sample entry of the V-PCC track and inthe scheme information of all video-coded V-PCC component tracks. Thebox may contain the V-PCC unit header for the data carried by therespective track.

aligned(8) class VPCCUnitHeaderBox extends FullBox(‘vunt’, version = 0,0) { vpcc_unit_header( )  unit_header; }

The box contains vpcc_unit_header( ) as above.

V-PCC Decoder Configuration Box

A V-PCC decoder configuration box may includeVPCCDecoderConfigurationRecord.

class VPCCConfigurationBox extends Box(‘vpcC’) {VPCCDecoderConfigurationRecord( ) VPCCConfig; }

This record contains a version field. This version may define version 1of this record. Incompatible changes to the record may be indicated by achange of version number. The decoder may determine whether to decodethis record or the bitstream based on the version number.

The VPCCParameterSet array includes a vpcc_parameter_set( ).

The SetupUnit arrays include atlas parameter sets that are constant forthe stream referred to by the sample entry in which the decoderconfiguration record as well as atlas sub-stream SEI messages ispresent.

The SetupUnit arrays may be constant for the stream referred to by thesample entry. The decoder configuration record may be present as well asatlas sub-stream SEI messages.

aligned(8) class VPCCDecoderConfigurationRecord { unsigned int(8)configurationVersion = 1; unsigned int(2) lengthSizeMinusOne; bit(1)reserved = 1; unsigned int(5) numOfVPCCParameterSets; for (i=0; i <numOfVPCCParameterSets; i++) { unsigned int(16) VPCCParameterSetLength;vpcc_unit(VPCCParameterSetLength) vpccParameterSet; // The parametervpccParameterSet is as defined in the standard document ISO/IEC 23090. }

For example, vpccParameterSet may contain information about point clouddata such as vps_v3c_parameter_set_id, vps_atlas_id, vps_frame_width[j],vps_frame_height[j], vps_multiple_map_streams_present_flag[j],occupancy_information(j), geometry_information(j), andattribute_information(j).

unsigned int(8) numOfSetupUnitArrays;

for (j=0; j < numOfSetupUnitArrays; j++) { bit(1) array_completeness;bit(1) reserved = 0; unsigned int(6) NAL_unit_type; unsigned int(8)numNALUnits; for (i=0; i < numNALUnits; i++) { unsigned int(16)SetupUnitLength; nal_unit(SetupUnitLength) setupUnit; // setupUnit is asdefined in ISO/IEC 23090-5. } }  }

configurationVersion is a version field. Incompatible changes to therecord may be indicated by a change of version number.

lengthSizeMinusOne plus 1 indicates the length in bytes of theNALUnitLength field in a V-PCC sample in the stream to which thisconfiguration record applies.

For example, a size of one byte is indicated with a value of 0. Thevalue of this field may be equal tossnh_unit_size_precision_bytes_minus1 in sample_stream_nal_header( ) forthe atlas substream.

numOfVPCCParameterSets specifies the number of V-PCC parameter set unitssignaled in the decoder configuration record.

VPCCParameterSetLength indicates the size, in bytes, of thevpccParameterSet field.

vpccParameterSet is a V-PCC unit of type VPCC VPS carrying thevpcc_parameter_set( ).

numOfSetupUnitArrays indicates the number of arrays of atlas NAL unitsof the indicated type(s).

array_completeness equal to 1 indicates that all atlas NAL units of thegiven type are in the following array and none are in the stream.array_completeness equal to 0 indicates that additional atlas NAL unitsof the indicated type may be in the stream. The default and permittedvalues are constrained by the sample entry name.

NAL_unit_type indicates the type of the atlas NAL units in the followingarray. It may be one of the values indicating the NAL_ASPS,NAL_PREFIX_SEI, or NAL_SUFFIX_SEI atlas NAL unit.

numNALUnits indicates the number of atlas NAL units of the indicatedtype included in the configuration record for the stream to which thisconfiguration record applies. The SEI array may only contain SEImessages.

SetupUnitLength indicates the size, in bytes, of the setupUnit field.The length field may include the size of both the NAL unit header andthe NAL unit payload, but does not include the length field itself.

setupUnit may contain a NAL unit of type NAL ASPS, NAL_AFPS,NAL_PREFIX_ESEI, NAL_PREFIX_NSEI, NAL_SUFFIX_ESEI, or NAL_SUFFIX_NSEI.

When not present in setupUnit, type NAL ASPS (atlas sequence parameterset), NAL AFPS (atlas frame parameter set), NAL_AAPS (atlas adaptationparameter), NAL_PREFIX_ESEI, NAL_PREFIX_NSEI, NAL_SUFFIX_ESEI, orNAL_SUFFIX_NSEI unit may be included. NAL_PREFIX_ESEI (Essentialsupplemental enhancement information, sei_rbsp( ), NAL_PREFIX_NSEI(Non-essential supplemental enhancement information, sei_rbsp( ),NAL_SUFFIX_ESEI (Essential supplemental enhancement information,sei_rbsp( ), or NAL_SUFFIX_NSEI(Non-essential supplemental enhancementinformation, sei_rbsp( ) may contain SEI messages. The SEI messages mayprovide information about the stream as a whole. An example of such anSEI may be a user-data SEI.

FIG. 44 shows a V-PCC atlas relation box according to embodiments.

FIG. 44 shows a V-PCC atlas relation box contained in a file (FIGS. 70to 72) or an item (FIG. 47) according to the V-PCC system.

The V-PCC atlas relation box according to the embodiments may includeVPCCAtlasRelationRecord according to the embodiments.

class VPCCAtlasRelationBox extends Box(‘vpcA’) { VPCCAtlasRelationRecordVPCCAtlas; }

VPCCAtlasRelationRecord is a structure for signaling an atlassub-bitstream containing multiple atlas data, and may containinformation such as a relationship between a list of atlas tile groupsincluded in the atlas data and an id and/or atlas data.

aligned(8) class VPCCAtlasRelationRecord { bit(1) entry_point_flag;unsigned int(8) num_atlas_data; for (i=0; i<num_atlas_data; i++) {unsigned int(8) atlas_id; unsigned int(8) num_atlas_tile_groups; for(j=0; j<num_atlas_tile_groups; j++) { unsigned int(16)atlas_tile_group_id; } unsigned int(8) num_vpcc_component_track_groups;for (k=0; k<num_vpcc_component_track_groups; k++) { unsigned int(32)vpcc_component_track_group_id; } unsigned int(8)num_vpcc_component_tracks; for (p=0; p<num_vpcc_component_tracks; p++) {unsigned int(32) vpcc_component_track_id; } } }

entry_point_flag is a flag having a value of true or false. When set totrue, it can be used to indicate a V-PCC track used as an entry pointamong multiple V-PCC tracks. Although it is recommended thatentry_point_flag be set to the value of true for only one V-PCC trackamong the multiple V-PCC tracks, the flag may be set to true for one ormore V-PCC tracks.

num_atlas_data may indicate the number of atlas data included in a V-PCCtrack.

atlas_id is an id for identifying atlas contained in the V-PCC track,and may be mapped to vuh_atlas_id of vpcc unit header( ) described inFIG. 27.

num_atlas_tile_groups may indicate the number of atlas tile groupscontained in atlas data.

atlas_tile_group_id is an id for identifying an atlas tile group, andmay be mapped to afti_tile_group_id of atlas_frame_tile_information( )described in FIG. 36.

num_vpcc_component_track_groups indicates the number of V-PCC componenttrack groups associated with the atlas data.

vpcc_component_track_group_id indicates the track group for the trackswhich carry the V-PCC components for the associated atlas data.

num_vpcc_component_tracks may indicate the number of associated V-PCCcomponent tracks when the V-PCC component tracks are not grouped.

vpcc_component_track id is an id for identifying each associated V-PCCcomponent track when the V-PCC component tracks are not grouped.

In addition, access to atlas data for each atlas tile group may bepossible through NALUMapEntry disclosed below.

NALUMapEntry may be present in the V-PCC track whenVPCCSpatialRegionsBox is present. For example, NALUMapEntry may beconfigured as specified in ISO/IEC14496-15.

The NALUMapEntry, when present, may be used to assign an identifier orgroupID to each atlas NAL unit.

The NALUMapEntry, when present, may or may not be linked to a samplegroup description setting grouping_type_parameter of theSampleToGroupBox of type ‘nalm’. Consequently, SampleToGroupBox of type‘nalm’ may or may not use version 0 of the box.

FIG. 45 shows a V-PCC global atlas information box according toembodiments.

FIG. 45 shows a V-PCC global atlas information box included in a file(FIGS. 70 to 72) or an item (FIG. 47) according to the V-PCC system.

V-PCC Global Atlas Information Box

A V-PCC global atlas information box may includeVPCCGlobalAtlasInformationRecord.

class VPCCGlobalAtlasInformationBox extends Box(‘vpcA’) {VPCCGlobalAtlasInformationRecord GlobalAtlas; }

VPCCGlobalAtlasInformationRecord is a structure for signaling multipleatlas data contained in all V-PCC tracks, and may contain informationsuch as a relationship between a list of atlas tile groups included inthe atlas data and ids and/or atlas data. OnlyVPCCGlobalAtlasInformationBox information may be contained in a V-PCCtrack with a sample entry including VPCCGlobalAtlasInformationBox, thatis, a separate V-PCC track, that is, a V-PCC main track.

aligned(8) class VPCCGlobalAtlasInformationRecord { unsigned int(8)num_vpcc_tracks; for (i=0; i<num_vpcc_tracks; i++) { unsigned int(8)track_id; bit(1) entry_point_flag; unsigned int(8) num_atlas_data;for(j=0; j<num_atlas_data; j++) { unsigned int(8) atlas_id; unsignedint(8) num_atlas_tile_groups; for (k=0; k<num_atlas_tile_groups; k++) {unsigned int(16) atlas_tile_group_id; } unsigned int(8)num_vpcc_component_track_groups; for (k=0;k<num_vpcc_component_track_groups; k++) { unsigned int(32)vpcc_component_track_group_id; } unsigned int(8)num_vpcc_component_tracks; for (p=0; p<num_vpcc_component_tracks; p++) {unsigned int(32) vpcc_component_track_id; } } } }

num_vpcc_tracks may indicate the number of V-PCC tracks.

track_id is an id for identifying V-PCC tracks.

entry_point_flag is a flag having a value of true or false. When set totrue, it can be used to indicate a V-PCC track used as an entry pointamong multiple V-PCC tracks. Although it is recommended thatentry_point_flag be set to the value of true for only one V-PCC trackamong the multiple V-PCC tracks, the flag may be set to true for one ormore V-PCC tracks.

num_atlas_data may indicate the number of atlas data contained in aV-PCC track having track_id.

atlas_id is an id for identifying atlas data contained in a V-PCC trackhaving track_id, and may be mapped to vuh_atlas_id of vpcc unit header() described in [Section 5.2 V-PCC].

num_atlas_tile_groups may indicate the number of atlas tile groupscontained in atlas data.

atlas_tile_group_id is an id for identifying an atlas tile group, andmay be mapped to afti_tile_group_id of atlas_frame_tile_information( )described in Atlas sub-bitstream and parameter sets in FIG. 36.

num_vpcc_component_track_groups indicates the number of V-PCC componenttrack groups associated with the atlas data.

vpcc_component_track_group_id indicates the track group for the trackswhich carry the V-PCC components for the associated atlas data.

num_vpcc_component_tracks may indicate the number of associated V-PCCcomponent tracks when the V-PCC component tracks are not grouped.

vpcc_component_track_id is an id for identifying each associated V-PCCcomponent track when the V-PCC component tracks are not grouped.

A file (FIGS. 70 to 72) or an item (FIG. 47) according to the V-PCCsystem may include a sample group according to embodiments.

Sample Group

V-PCC Atlas Parameter Set Sample Group

The ‘vaps’ grouping_type for sample grouping represents the assignmentof samples in a V-PCC track to the atlas parameter sets carried in thissample group. When SampleToGroupBox with grouping_type equal to ‘vaps’is present, SampleGroupDescriptionBox with the same grouping type may bepresent, and may contain an ID of the group to which the samples belong.

A V-PCC track may contain at most one SampleToGroupBox withgrouping_type equal to ‘yaps’. aligned(8) classVPCCAtlasParamSampleGroupDescriptionEntry( ) extends

SampleGroupDescriptionEntry(‘vaps') { unsigned int(8) numOfSetupUnits;for (i=0; i < numOfSetupUnits; i++) { unsigned int(16) setupUnitLength;nal_unit(setupUnitLength) setupUnit; }

numOfAtlasParameterSets specifies the number of atlas parameter setssignaled in the sample group description.

atlasParameterSet is a sample_stream_vpcc_unit( ) instance containing anatlas sequence parameter set, atlas frame parameter set associated withthis group of samples.

According to embodiments, it may be specified as follows. aligned(8)class VPCCAtlasParamSampleGroupDescriptionEntry( ) extends

SampleGroupDescriptionEntry(‘vaps') { unsigned int(3)lengthSizeMinusOne; unsigned int(5) numOfAtlasParameterSets; for (i=0;i<numOfAtlasParameterSets; i++) { sample_stream_nal_unitatlasParameterSetNALUnit; } }

lengthSizeMinusOne plus 1 indicates the precision, in bytes, of thessnu_nal_unit_size element in all sample stream NAL units signaled inthis sample group description.

atlasParameterSetNALUnit is a sample_stream_nal_unit( ) instancecontaining an atlas sequence parameter set, atlas frame parameter setassociated with this group of samples.

A file in accordance with embodiments may include one or more tracksincluding signaling information for point cloud data.

A track in accordance with embodiments may include one or more atlasidentifier information to represent one or more atlas data for pointcloud data.

A track in accordance with embodiments may include one or more atlastile information associated with atlas data.

One or more atlas identifier information in accordance with embodimentsmay be carried in a sample entry of a track.

One or more atlas tile identifier information in accordance withembodiments may represent that atlas data may include one or more atlastiles for point cloud data.

A track in accordance with embodiments further includes component trackinformation for atlas data.

FIG. 46 shows a dynamic atlas relation sample group and a dynamic globalatlas information sample group according to embodiments.

FIG. 46 shows a dynamic atlas relation sample group and a dynamic globalatlas information sample group included in a file (FIGS. 70 to 72) or anitem (FIG. 47) according to the V-PCC system.

Dynamic Atlas Relation Sample Group

The ‘dyar’ grouping_type for sample grouping represents the assignmentof samples in a V-PCC track to an atlas relation box carried in thissample group. When SampleToGroupBox with grouping_type equal to ‘dyar’is present, SampleGroupDescriptionBox with the sample grouping type maybe present, and may contain the ID of this group of samples.

A V-PCC track may contain at most one SampleToGroupBox withgrouping_type equal to ‘dyar’

aligned(8) class DynamicAtlasRelationSampleGroupDescriptionEntry( )extends SampleGroupDescriptionEntry(‘dyar’) { VPCCAtlasRelationBox( ); }

Dynamic Global Atlas Information Sample Group

The ‘dyga’ grouping_type for sample grouping represents the assignmentof samples in V-PCC track to an atlas relation box carried in thissample group. When SampleToGroupBox with grouping_type equal to ‘dyga’is present, SampleGroupDescriptionBox with the samp grouping type may bepresent, and may contain the ID of this group of samples.

A V-PCC main track may contain at most one SampleToGroupBox withgrouping_type equal to ‘dyga’.

aligned(8) classDynamicGlobalAtlasInformationSampleGroupDescriptionEntry( ) extendsSampleGroupDescriptionEntry(‘dyar’) { VPCCGlobalAtlasInformationBox( );}

Tracks of a file (FIGS. 70 to 72) or an item (FIG. 47) according to theV-PCC system may be grouped.

Track Grouping

Spatial Region Track Grouping

TrackGroupTypeBox with track_group_type equal to ‘3drg’ indicates thatthis track belongs to a group of V-PCC component tracks that correspondto a 3D spatial region. Tracks belonging to the same spatial region havethe same value of track_group_id for track_group_type ‘3drg’. Thetrack_group_id of tracks from one spatial region differs from thetrack_group_id of tracks from any other spatial region.

aligned(8) class SpatialRegionGroupBox extends TrackGroupTypeBox(‘3drg’){ }

V-PCC Track Grouping

TrackGroupTypeBox with track_group_type equal to ‘atrg’ indicates thatthis track belongs to a group of V-PCC tracks that correspond tospecific atlas data and/or V-PCC content. V-PCC tracks related to theatlas data and/or V-PCC content have the same value of track_group_idfor track_group_type ‘atrg’.

V-PCC track grouping may be used to group V-PCC tracks corresponding tospecific atlas data, and/or may be used to group V-PCC tracksconstituting one V-PCC content.

aligned(8) class AtlasRelationGroupBox extends TrackGroupTypeBox(‘atrg’){ bit(1) entry_point_flag; }

entry_point_flag is a flag having a value of true or false. When set totrue, it can be used to indicate a V-PCC track group used as an entrypoint among multiple V-PCC track groups. Although it is recommended thatentry_point_flag be set to the value of true for only one V-PCC trackgroup among the multiple V-PCC track groups, the flag may be set to truefor one or more V-PCC track groups.

V-PCC Component Track Grouping

TrackGroupTypeBox with track_group_type equal to ‘vctg’ indicates thatthis track belongs to a group of V-PCC component tracks that correspondto atlas data and/or V-PCC content. V-PCC component tracks related tothe atlas data and/or V-PCC content have the same value oftrack_group_id for track_group_type ‘vctg’.

V-PCC component track grouping may be used to group V-PCC componenttracks corresponding to specific atlas data, and/or may be used to groupV-PCC component tracks constituting one V-PCC content.

aligned(8) class VPCCComponentTrackGroupBox extendsTrackGroupTypeBox(‘vctg’) { bit(1) entry_point_flag; }

entry_point_flag is a flag having a value of true or false. When set totrue, it can be used to indicate a V-PCC component track group used asan entry point among multiple V-PCC component track groups. Although itis recommended that entry_point_flag be set to the value of true foronly one V-PCC component track group among the multiple V-PCC componenttrack groups, the flag may be set to true for one or more V-PCCcomponent track groups.

A track of a file (FIGS. 70 to 72) or an item (FIG. 47) according to theV-PCC system may have the following structure.

Multi Track Container of V-PCC Bitstream

In the general layout of a multi-track ISOBMFF V-PCC container, V-PCCunits in a V-PCC bitstream may be mapped to individual tracks within thecontainer file based on the types thereof. An example is shown in FIGS.40 and 41. There may be two types of tracks in a multi-track ISOBMFFV-PCC container: V-PCC track and V-PCC component track.

V-PCC component tracks are video scheme tracks which carry 2D videoencoded data for the occupancy map, geometry, and attributesub-bitstreams of the V-PCC bitstream. In addition, the followingconditions may be satisfied for V-PCC component tracks:

a) in the sample entry, a new box documenting the role of the videostream contained in this track may be inserted in the V-PCC system;

b) a track reference may be introduced from the V-PCC track into theV-PCC component track to establish the membership of the V-PCC componenttrack in the specific point cloud represented by the V-PCC track;

c) the track-header flags may be set to 0 to indicate that this trackdoes not contribute directly to the overall layup of the movie butcontributes to the V-PCC system.

Tracks belonging to the same V-PCC sequence are time-aligned. Samplesthat contribute to the same point cloud frame across the differentvideo-encoded V-PCC component tracks and the V-PCC track has the samepresentation time. The V-PCC atlas sequence parameter sets and atlasframe parameter sets used for such samples have a decoding time equal orprior to the composition time of the point cloud frame. In addition, alltracks belonging to the same V-PCC sequence have the same implicit orexplicit edit lists. Synchronization between the elementary streams inthe component tracks are handled by the ISOBMFF track timing structures(stts, ctts, and cslg), or equivalent mechanisms in movie fragments.

The sync samples in the V-PCC track and V-PCC component tracks may ormay not be time-aligned. In the absence of time-alignment, random accessmay involve pre-rolling the various tracks from different syncstart-times in order to enable starting at the desired time.

In the case of time-alignment (required by, for example, a V-PCC profilesuch as the basic toolset profile as defined in V-PCC), the sync samplesof the V-PCC track may be considered as the random access points for theV-PCC content, and random access may be performed by only referencingthe sync sample information of the V-PCC track.

Based on this layout, a V-PCC ISOBMFF container may include thefollowing:

The container file may include one or more V-PCC tracks which containV-PCC parameter sets and atlas sub-bitstream parameter sets (in thesample entry) and samples carrying atlas sub-bitstream NAL units. Thistrack also includes track references to other tracks carrying thepayloads of video compressed V-PCC units (of unit types VPCC_OVD,VPCC_GVD, and VPCC_AVD);

The container file may include a video scheme track in which the samplescontain access units of a video-coded elementary stream for occupancymap data (i.e., payloads of V-PCC units of type VPCC_OVD);

The container file may include one or more video scheme tracks in whichthe samples contain access units of video-coded elementary streams forgeometry data (i.e., payloads of V-PCC units of type VPCC_GVD); and

The container file may include zero or more video scheme tracks in whichthe samples contain access units of video-coded elementary streams forattribute data (i.e., payloads of V-PCC units of type VPCC_AVD).

V-PCC Track

A file (FIGS. 70 to 72) or an item (FIG. 47) according to the V-PCCsystem may include the following information in a track.

V-PCC Track Sample Entry

Sample Entry Type: ‘vpcl’, ‘vpcg’, ‘vpga’

Container: SampleDescriptionBox

Mandatory: A ‘vpcl’ or ‘vpcg’ sample entry is mandatory

Quantity: One or more sample entries may be present

A track according to embodiments may include sample entry types referredto as ‘vpcl’, ‘vpcg’, and ‘vpga’.

V-PCC tracks may use VPCCSampleEntry which extendsVolumetricVisualSampleEntry with a sample entry type of ‘vpcl’ or‘vpcg’.

A VPCC track sample entry may contain a VPCCConfigurationBox.

Under the ‘vpcl’ sample entry, all atlas sequence parameter sets, atlasframe parameter sets, or V-PCC SEIs may be present in the setupUnitarray.

Under the ‘vpcg’ sample entry, the atlas sequence parameter sets, atlasframe parameter sets, V-PCC SEIs may be present in this array, or in thestream.

When multiple atlas data are composed of multiple V-PCC tracks, thepoint cloud reception device according to the embodiments may parse theV-PCC tracks, and recognize the relationship between the atlas data andthe atlas tile groups and information about the associated V-PCCcomponent tracks through VPCCAtlasRelationBox that may be contained inVPCCSampleEntry.

An optional BitRateBox may be present in the VPCC volumetric sampleentry to signal the bit rate information of the V-PCC track.

aligned(8) class VPCCSampleEntry( ) extends VolumetricVisualSampleEntry(‘vpc1’) { VPCCConfigurationBox config; VPCCAtlasRelationBox atlas;VPCCUnitHeaderBox unit_header; }

The method or device according to the embodiments may configure aseparate V-PCC track, that is, a V-PCC main track, using a VPCCGlobalAtlasInformationBox, and set the sample entry type to ‘vpga’.

The point cloud device according to the embodiments may first parse atrack having a sample entry of the type ‘vpga’ and acquire informationof other V-PCC tracks contained in the file and atlas data informationthat each track has.

That is, when the sample entry type of the V-PCC track is ‘vpga’, thetrack may be a track used as an entry point.

The method or device according to the embodiments may always set thetrack id of a track with a sample entry of type ‘vpga’ to 1.

aligned(8) class VPCCSampleEntry( ) extendsVolumetricVisualSampleEntry(‘vpga’) { VPCCGlobalAtlasInformationBoxglobalAtlas; }

V-PCC Track Sample Format

Each sample in the V-PCC track may correspond to a single coded atlasaccess unit.

Samples corresponding to this frame in the various component tracks mayhave the same composition time as the V-PCC track sample.

Each V-PCC sample may contain one V-PCC unit payload of type VPCC AD,which may include one or more atlas NAL units.

aligned(8) class VPCCSample {  unsigned int PointCloudPictureLength =sample_size; // size of sample (e.g., from SampleSizeBox)  for (i=0;i<PointCloudPictureLength; ) { sample_stream_nal_unit nalUnit; i +=(VPCCDecoderConfigurationRecord.lengthSizeMinusOne+1) *nalUnit.ssnu_nal_unit_size; } }

nalUnit may contain a single atlas NAL unit in NAL unit sample streamformat.

V-PCC Track Sync Sample

A sync sample in a V-PCC track may be a sample that contains an intrarandom access point (TRAP) coded atlas access unit.

According to embodiments, atlas sub-bitstream parameter sets (e.g.,ASPS, AAPS, AFPS) and SEI messages may be repeated, if needed, at a syncsample to allow for random access.

Referencing V-PCC Tracks

The method/device according to the embodiments may encapsulate atlasdata using multiple V-PCC tracks.

When a V-PCC main track with a sample entry type of ‘vpga’ is used, asmany TrackReferenceTypeBoxes as the number of V-PCC tracks may be addedto TrackReferenceBox of TrackBox of the V-PCC main track.TrackReferenceTypeBox may include track IDs of V-PCC tracks referencedby the V-PCC main track. The reference type referring to V-PCC tracksmay be ‘vpct’.

Video-Encoded V-PCC Component Tracks

Since it is not meaningful to display the decoded frames from attribute,geometry, or occupancy map tracks without reconstructing the point cloudat the player side, a restricted video scheme type may be defined forthe video-coded tracks.

V-PCC component video tracks may be represented in the file asrestricted video, and may be identified by ‘pccv’ in the scheme typefield of the SchemeTypeBox of the RestrictedSchemeInfoBox of theirrestricted video sample entries.

It should be noted that there is no restriction on the video codec usedfor encoding the attribute, geometry, and occupancy map V-PCCcomponents. These components may be encoded using different videocodecs.

Scheme Information

A SchemeInformationBox may be present and contain a VPCCUnitHeaderBox.

Referencing V-PCC Component Tracks

To link a V-PCC track to component video tracks, threeTrackReferenceTypeBoxes are added to a TrackReferenceBox within theTrackBox of the V-PCC track, one for each component. TheTrackReferenceTypeBox contains an array of track_IDs designating thevideo tracks which the V-PCC track references. The reference type of aTrackReferenceTypeBox identifies the type of the component (i.e.,occupancy map, geometry, or attribute, or occupancy map). The 4CCs ofthese track reference types may be specified as follows:

‘pcco’: the referenced track(s) contain the video-coded occupancy mapV-PCC component;

‘pccg’: the referenced track(s) contain the video-coded geometry V-PCCcomponent; and

‘pcca’: the referenced track(s) contain the video-coded attribute V-PCCcomponent.

The type of the V-PCC component carried by the referenced restrictedvideo track, and signaled in the RestrictedSchemelnfoBox of the track,may match the reference type of the track reference from the V-PCCtrack.

Single Track Container of V-PCC Bitstream

A single-track encapsulation of V-PCC data requires the V-PCC encodedelementary bitstream to be represented by a single track.

Single-track encapsulation of PCC data may be utilized in the case ofsimple ISOBMFF encapsulation of a V-PCC encoded bitstream. Such abitstream may be directly stored as a single track without furtherprocessing. V-PCC unit header data structures may be kept in thebitstream. A single track container may be provided to media workflowsfor further processing (e.g., multi-track file generation, transcoding,DASH segmentation, etc.).

V-PCC Bitstream Track

Sample Entry Type: ‘vpel’, ‘vpeg’

Container: SampleDescriptionBox

Mandatory: A ‘vpel’ or ‘vpeg’ sample entry is mandatory

Quantity: One or more sample entries may be present

V-PCC bitstream tracks use VolumetricVisualSampleEntry with a sampleentry type of ‘vpel’ or ‘vpeg’.

A VPCC bitstream sample entry contains a VPCCConfigurationBox.

Under the ‘vpel’ sample entry, all atlas sequence parameter sets, atlasframe parameter sets, SEIs may be present in the setupUnit array.

Under the ‘vpeg’ sample entry, atlas sequence parameter sets, atlasframe parameter sets, SEIs may be present in this array, or in thestream.

aligned(8) class VPCCBitStreamSampleEntry( ) extendsVolumetricVisualSampleEntry (‘vpe1’) { VPCCConfigurationBox config; }

V-PCC Bitstream Sample Format

A V-PCC bitstream sample contains one or more V-PCC units which belongto the same presentation time, i.e, one V-PCC access unit. A sample maybe self-contained like a sync sample or decoding-wise dependent on othersamples of V-PCC bitstream track.

V-PCC Bitstream Sync Sample

A V-PCC bitstream sync sample satisfies all the following conditions:

It is independently decodable;

None of the samples that come after the sync sample in decoding orderhave any decoding dependency on any sample prior to the sync sample; and

All samples that come after the sync sample in decoding order aresuccessfully decodable.

V-PCC Bitstream Sub-Sample

A V-PCC bitstream sub-sample is a V-PCC unit which is contained in aV-PCC bitstream sample.

A V-PCC bitstream track shall contain one SubSampleInformationBox inSampleTableBox, or in the TrackFragmentBox of each of theMovieFragmentBoxes, which lists the V-PCC bitstream sub-samples. The32-bit unit header of the V-PCC unit which represents the sub-sample maybe copied to the 32-bit codec specific parameters field of thesub-sample entry in the Sub SampleInformationBox. The V-PCC unit type ofeach sub-sample may be identified by parsing the codec specificparameters field of the sub-sample entry in the SubSampleInformationBox.

Timed Metadata Track

In the method/device according to the embodiments, V-PCC atlas relationinformation may be delivered based on the configuration of a timedmetadata track as follows.

If the V-PCC track has an associated timed-metadata track with a sampleentry type ‘dyat’, atlas data defined for the point cloud stream carriedby the V-PCC track may be considered as dynamic atlas data.

The associated timed-metadata track may contain a ‘cdsc’ track referenceto the V-PCC track carrying the atlas stream.

Sample Entry

aligned(8) class DynamicAtlasRelationSampleEntry extendsMetaDataSampleEntry(‘dyat’){ VPCCAtlasRelationBox( ); }

Sample Format

aligned(8) class DynamicAtlasRelationSample( ) { bit(1)entry_point_flag; unsigned int(8) num_atlas_data; for (i=0;i<num_atlas_data; i++) { unsigned int(8) atlas_id; unsigned int(8)num_atlas_tile_groups; for (j=0; j<num_atlas_tile_groups; j++) {unsigned int(16) atlas_tile_group_id; } unsigned int(8)num_vpcc_component_track_groups; for (k=0;k<num_vpcc_component_track_groups; k++) { unsigned int(32)vpcc_component_track_group_id; } unsigned int(8)num_vpcc_component_tracks; for (p=0; p<num_vpcc_component_tracks; p++) {unsigned int(32) vpcc_component_track_id; } } }

The semantics for each field are the same as defined inVPCCAtlasRelationRecord.

In addition, when the V-PCC global atlas information changesdynamically, it may be included in the sample entry of thetimed-metadata track, and only changing information may be included inthe sample.

Sample Entry

aligned(8) class DynamicGlobalAtlasInformationSampleEntry extendsMetaDataSampleEntry(‘dyga’) { VPCCGlobalAtlasInformationBox( ); }

Sample Format

aligned(8) class GlobalAtlasInformationSample( ) { unsigned int(8)num_vpcc_tracks; for (i=0; i<num_vpcc_tracks; i++) { unsigned int(8)track_id; bit(1) entry_point_flag; unsigned int(8) num_atlas_data;for(j=0, j<num_atlas_data; j++) { unsigned int(8) atlas_id; unsignedint(8) num_atlas_tile_groups; for (k=0; k<num_atlas_tile_groups; k++) {unsigned int(16) atlas_tile_group_id; } unsigned int(8)num_vpcc_component_track_groups; for (k=0;k<num_vpcc_component_track_groups; k++) { unsigned int(32)vpcc_component_track_group_id; } unsigned int(8)num_vpcc_component_tracks; for (p=0; p<num_vpcc_component_tracks; p++) {unsigned int(32) vpcc_component_track_id; } } } }

The semantics for each field are the same as defined inVPCCGlobalAtlasInformationRecord.

FIG. 47 shows an overview of a structure for encapsulating non-timedV-PCC data according to embodiments.

FIG. 47 shows a structure for transmitting non-timed V-PCC data when thepoint cloud data related device of FIGS. 20 to 22 processes non-timedpoint cloud data.

The point cloud data transmission/reception method/device according tothe embodiments, and a system included in the transmission/receptiondevice may transmit and receive non-timed V-PCC data by encapsulatingnon-timed V-PCC data as shown in FIG. 47.

When the point cloud data according to the embodiments is an image, thepoint cloud video encoder 10002 of FIG. 1 (or the encoder of FIG. 4, theencoder of FIG. 15, the transmission device of FIG. 18, the processor20001 of FIG. 20, the encoder 20003 of FIG. 20, the processor of FIG.21, the image encoder 21008 of FIG. 21) may encode the image, and thefile/segment encapsulator 10003 (or the file/segment encapsulator 20004of FIG. 20, the file/segment encapsulator 21009 of FIG. 21) may storethe image and image-related information in a container (item) as shownin FIG. 47. The transmitter 10004 may transmit the container.

Similarly, the receiver of FIG. 1 receives the container of FIG. 47, andthe file/segment decapsulator 10007 (or the file/segment decapsulator20005 of FIG. 20, the file/segment decapsulator 22000) parses thecontainer. The point cloud video decoder 10008 of FIG. 1 (or the decoderof FIG. 16, the decoder of FIG. 17, the reception device of FIG. 19, theimage decoder 20006, or the image decoder 22002) may decode the imagecontained in the item and provide the decoded image to the user.

The image according to the embodiments may be a still image. Themethod/device according to the embodiments may transmit/receive pointcloud data about the image. The method/device according to theembodiments may store the image in an item based on the data containerstructure as shown in FIG. 47 and transmit/receive the same. Also,attribute information about the image may be stored in an image propertyor the like.

The non-timed V-PCC data is stored in a file as image items. Two newitem types (i.e., V-PCC item and V-PCC unit item) are defined forencapsulating non-timed V-PCC data.

A new handler type 4CC code ‘vpcc’ is defined and stored in theHandlerBox of the MetaBox in order to indicate the presence of V-PCCitems, V-PCC unit items and other V-PCC encoded content representationinformation.

V-PCC Items 47000: A V-PCC item is an item which represents anindependently decodable V-PCC access unit. An item type ‘vpci’ isdefined to identify V-PCC items. V-PCC items store V-PCC unit payload(s)of the atlas sub-bitstream. When PrimaryItemBox is present, item id inthis box is set to indicate a V-PCC item.

A V-PCC unit item is an item which represents a V-PCC unit data. V-PCCunit items store V-PCC unit payload(s) of occupancy, geometry, andattribute video data units. A V-PCC unit item stores only one V-PCCaccess unit related data.

An item type for a V-PCC unit item is set depending on the codec used toencode corresponding video data units. A V-PCC unit item is associatedwith corresponding V-PCC unit header item property and codec specificconfiguration item property. V-PCC unit items are marked as hidden itemsbecause it is not meaningful to display the same independently.

In order to indicate the relationship between a V-PCC item and V-PCCunit items, the following three item reference types are used. Itemreference is defined “from” a V-PCC item “to” the related V-PCC unititems.

‘pcco’: the referenced V-PCC unit item(s) contain the occupancy videodata units.

‘pccg’: the referenced V-PCC unit item(s) contain the geometry videodata units.

‘pcca’: the referenced V-PCC unit item(s) contain the attribute videodata units.

V-PCC Configuration Item Property 47020

Box Types: ‘vpcp’

Property type: Descriptive item property

Container: ItemPropertyContainerBox

Mandatory (per item): Yes, for a V-PCC item of type ‘vpci’

Quantity (per item): One or more for a V-PCC item of type ‘vpci’

For the V-PCC configuration item property, the box type is ‘vpcp’ andthe property type is a descriptive item property. The container is anItemPropertyContainerBox. It is mandatory per item for a V-PCC item oftype ‘vpci’. One or more properties per item may be present for a V-PCCitem of type ‘vpci’.

V-PCC parameter sets are stored as descriptive item properties and areassociated with the V-PCC items.

aligned(8) class vpcc_unit_payload_struct ( ) { unsigned int(16)vpcc_unit_payload_size; vpcc_unit_payload( ); } aligned(8) classVPCCConfigurationProperty extends ItemProperty(‘vpcc’) {vpcc_unit_payload_struct( )[ ]; }

vpcc_unit_payload size specifies the size in bytes of thevpcc_unit_paylod( ).

vpcc_unit_paylod( ) includes a V-PCC unit of type VPCC_VPS.

V-PCC Unit Header Item Property 47030

Box Types: ‘vunt’

Property type: Descriptive item property

Container: ItemPropertyContainerBox

Mandatory (per item): Yes, for a V-PCC item of type ‘vpci’ and for aV-PCC unit item

Quantity (per item): One

For the V-PCC unit header item property, the box type is ‘vunt’, theproperty type is a descriptive item property, and the container is anItemPropertyContainerBox. It is Mandatory per item for a V-PCC item oftype ‘vpci’ and for a V-PCC unit item. One property may be present peritem.

V-PCC unit header is stored as descriptive item properties and isassociated with the V-PCC items and the V-PCC unit items.

aligned(8) class VPCCUnitHeaderProperty ( ) extendsItemFullProperty(‘vunt’, version=0, 0) { vpcc_unit_header( ); }

Based on the structure of FIG. 47, the method/device/system according tothe embodiments may deliver non-timed point cloud data.

Carriage of Non-timed Video-based Point Cloud Compression Data

The non-timed V-PCC data is stored in a file as image items. A newhandler type 4CC code ‘vpcc’ is defined and stored in the HandlerBox ofthe MetaBox in order to indicate the presence of V-PCC items, V-PCC unititems and other V-PCC encoded content representation information.

An item according to embodiments represents an image. For example, it isdata that does not move and may refer to a single image.

The method/device according to the embodiments may generate and transmitdata according to the embodiments based on a structure for encapsulatingnon-timed V-PCC data, as shown in FIG. 45.

V-PCC Items

A V-PCC item is an item which represents an independently decodableV-PCC access unit. A new item type 4CC code ‘vpci’ is defined toidentify V-PCC items. V-PCC items store V-PCC unit payload(s) of atlassub-bitstream.

If PrimaryItemBox exists, item_id in this box shall be set to indicate aV-PCC item.

V-PCC Unit Item

A V-PCC unit item is an item which represents a V-PCC unit data.

V-PCC unit items store V-PCC unit payload(s) of occupancy, geometry, andattribute video data units. A V-PCC unit item may contain only one V-PCCaccess unit related data.

An item type 4CC code for a V-PCC unit item is set based on the codecused to encode corresponding video data units. A V-PCC unit item isassociated with corresponding V-PCC unit header item property and codecspecific configuration item property.

V-PCC unit items are marked as hidden items, since it is not meaningfulto display independently.

In order to indicate the relationship between a V-PCC item and V-PCCunits, three new item reference types with 4CC codes ‘pcco’, ‘pccg’ and‘pcca’ are defined. Item reference is defined “from” a V-PCC item “to”the related V-PCC unit items. The 4CC codes of item reference types are:

‘pcco’: the referenced V-PCC unit item(s) containing the occupancy videodata units.

‘pccg’: the referenced V-PCC unit item(s) containing the geometry videodata units.

‘pcca’: the referenced V-PCC unit item(s) containing the attribute videodata units.

V-PCC-Related Item Properties

Descriptive item properties are defined to carry the V-PCC parameter setinformation and V-PCC unit header information, respectively:

V-PCC Configuration Item Property

Box Types: ‘vpcp’

Property type: Descriptive item property

Container: ItemPropertyContainerBox

Mandatory (per item): Yes, for a V-PCC item of type ‘vpci’

Quantity (per item): One or more for a V-PCC item of type ‘vpci’

V-PCC parameter sets are stored as descriptive item properties and areassociated with the V-PCC items.

essential is set to 1 for a ‘vpcp’ item property.

aligned(8) class vpcc_unit_payload_struct ( ) { unsigned int(16)vpcc_unit_payload_size; vpcc_unit_payload( ); } aligned(8) classVPCCConfigurationProperty extends ItemProperty(‘vpcc’) {vpcc_unit_payload_struct( )[ ]; }

vpcc_unit_payload_size specifies the size in bytes of thevpcc_unit_paylod( ).

V-PCC Unit Header Item Property

Box Types: ‘vunt’

Property type: Descriptive item property

Container: ItemPropertyContainerBox

Mandatory (per item): Yes, for a V-PCC item of type ‘vpci’ and for aV-PCC unit item

Quantity (per item): One

V-PCC unit header is stored as descriptive item properties and isassociated with the V-PCC items and the V-PCC unit items.

The essential is set to 1 for a ‘vunt’ item property.

aligned(8) class VPCCUnitHeaderProperty ( ) { extendsItemFullProperty(‘vunt’, version=0, 0) { vpcc_unit_header( ); }

FIG. 48 illustrates a file encapsulation operation for multiple atlasdata according to embodiments.

FIG. 48 illustrates the operation of the file encapsulators 10003,20004, and 21009.

The point cloud data transmission device according to the embodimentsmay include a file encapsulator (hereinafter, referred to as anencapsulator) and/or a transmitter. The encapsulator may configure aV-PCC bitstream in the isobmff file format and create a box structure orthe like necessary for encoding in the isobmff file format. Thetransmitter may transmit the generated data. Each step in FIG. 48 isdescribed below.

0. A bitstream V-PCC-encoded by the encoder (10002, FIG. 4, FIG. 15,FIGS. 18, 20000 to 20003, 21000 to 21008) (i.e., input bitstream, FIG.25, FIG. 26, or FIG. 31) may be used as an input.

1. A V-PCC track may be created in an ISOBMFF file (FIGS. 70 to 72, FIG.47).

2. A sample entry may be created in the V-PCC track created in operation1 above.

3. VPS (VPCC Parameter Set) info (see FIG. 29) according to embodimentsmay be acquired from the input bitstream.

4. The VPS info according to the embodiments may be added to the sampleentry.

5. Atlas data info according to embodiments may be acquired from theinput bitstream. The atlas data info according to the embodiments mayinclude VPCCAtlasRelation information.

6. Based on the atlas data info according to the embodiments, aVPCCAtlasRelationBox structure suitable for the point cloud system fileformat may be created and added to a sample entry.

7. Atlas VPCC unit header info according to embodiments may be acquiredfrom the input bitstream.

8. VPCC unit header info according to the embodiments may be added to asample entry.

9. Atlas NAL unit data according to embodiments may be added to a sampleentry or a sample according to nalType.

10. Data according to embodiments except for NAL_ASPS or NAL_XXXX_SEI,which is an atlas NAL unit data type, may be added to a sample.

11. The sample created in operation 10 above may be added to the V-PCCtrack.

FIG. 49 illustrates a file decapsulation operation for atlas dataaccording to embodiments.

FIG. 49 illustrates the operation of the file decapsulators 10007,20005, and 22000.

The point cloud data reception device according to the embodiments mayinclude a receiver and/or a file/segment decapsulator (which may bereferred to as a decapsulator). The receiver may receive point clouddata (in the V-PCC isobmff file format). The decapsulator maydecapsulate the V-PCC isobmff file into a V-PCC bitstream, and may parsea box structure (information in the file) or the like required fordecoding thereof. The reception device may further include a decoder.The decoder may decode the V-PCC bitstream. Each operation of thedecapsulator according to the embodiments is described below.

0. A file encapsulated in V-PCC Isobmff (FIGS. 70 to 72 and 47) may bereceived.

1. VPS (V-PCC Parameter Set, FIG. 29) information according to theembodiments may be acquired from the sample entry of the input isobmfffile.

2. The VPS information acquired in operation 1 above may be configuredin the form of a V-PCC bitstream (FIG. 25, FIG. 26, FIG. 31).

3. V-PCC unit header information according to the embodiments may beacquired from the sample entry of the input isobmff file.

4. The V-PCC unit header information acquired in operation 3 above maybe configured in the form of a V-PCC bitstream.

5. VPCCAtlasRelation information according to the embodiments may beacquired from the sample entry of the input isobmff file.

6. V-PCC configuration information according to the embodiments may beacquired from the sample entry of the input isobmff file. According toembodiments, the V-PCC configuration information includes VPS and atlasdata in which NAL unit type is NAL_ASPS or NAL_XXXX_SEI.

7. From the sample of the input isobmff file, atlas data according toembodiments having the NAL unit type such as TSA may be acquired.

8. Based on the VPCCAtlasRelation information acquired in operation 5above, the atlas data that matches vuh_atlas_id of the atlas vpcc unitheader information acquired in operation 7 above may be aggregated. Inaddition, atlas NAL units that match atlas tile_group_id at the atlastile group level may be aggregated.

9. SampleStreamNalUnit data constituting the V-PCC atlas sub-bitstream(FIG. 31) may be configured using the atlas data acquired in operations6 to 8 above.

10. A V-PCC atlas sub-bitstream for V-PCC bitstream decoding may beconfigured.

11. By parsing the V-PCC atlas sub-bitstream generated in operation 10above through VPCCBitstreamDecoder, an atlas tile group and patch datanecessary for reconstructing a point cloud according to embodiments maybe acquired.

FIG. 50 illustrates file level signaling according to embodiments.

FIG. 50 illustrates a reference and/or grouping relationship of a V-PCCtrack according to embodiments.

The method/device according to the embodiments may deliver point clouddata in multiple tracks.

The relationship between the V-PCC bitstream and the V-PCC file formatstructure may be represented as shown in FIG. 50.

When point cloud data for multiple atlas is processed, V-PCC track 1 mayhave a sample entry type ‘vpcl’ (=all atlas sequence parameter sets,atlas frame parameter sets, or V-PCC SEIs), and contain data aboutatlas 1. V-PCC track 2 may have a sample entry type ‘vpcl’ (=all atlassequence parameter sets, atlas frame parameter sets, or V-PCC SEIs), andcontain data about atlas 2 and/or atlas 3.

Sample entries of all V-PCC tracks may contain VPCCAtlasRelationBox.

Track 1 may have a reference relationship with a V-PCC component trackgroup based on a track reference. For example, a group of a V-PCCcomponent track carrying occupancy video data about atlas 1, a V-PCCcomponent track carrying geometry video data, and a V-PCC componenttrack carrying attribute video data and V-PCC track 1 may refer to eachother.

Track 2 may have a reference relationship with the V-PCC component trackgroup based on the track reference. For example, a group of a V-PCCcomponent track carrying occupancy video data about atlas 2, a V-PCCcomponent track carrying geometry video data, and a V-PCC componenttrack carrying attribute video data and V-PCC track 1 may refer to eachother.

The method/device according to the embodiments may provide an effect ofefficiently accessing multiple atlases and point cloud data about theatlases, and efficiently decoding and rendering desired point clouddata.

FIG. 51 illustrates file level signaling according to embodiments.

FIG. 51 illustrates an additional file signaling operation, as shown inFIG. 50.

V-PCC main track 1 may have a sample entry type of ‘vpga’ and containVPCCGlobalAtlasInformationBox. V-PCC main track 1 may have a trackreference relationship with V-PCC track 2 about atlas 1 and/or V-PCCtrack 3 about atlas 2 or atlas 3. In addition, the V-PCC track 2 and/orV-PCC track 3 may have a reference relationship with a V-PCC componenttrack group.

The method/device according to the embodiments may parse the sampleentry of the main track, efficiently access desired point cloud databased on file level signaling of the atlas data and the video componentdata of the point cloud data as shown in FIGS. 50 and 51, and mayprocess necessary data.

FIG. 52 shows structures of a V-PCC bitstream and a V-PCC file formataccording to embodiments.

FIG. 52 illustrates a relationship between a bitstream according toFIGS. 25, 26, 31, and the like and a file format according to FIGS. 70to 72, 47, and the like.

One or more patches of point cloud data are included in an atlas tilegroup, and the atlas tile group is included in an atlas frame. One atlasmay be represented as one atlas frame. According to the configuration ofthe point cloud data, the atlas tile group may include one patch ormultiple patches, and may include one atlas tile group or multiple atlastile groups. As the object of the point cloud data is projected, one ormore atlas tile groups may be included in the atlas frame.

The V-PCC bitstream according to the embodiments encoded by the encoderaccording to the embodiments may contain a sample stream VPCC unit or aNAL unit (FIGS. 25 and 26).

A unit contained in the bitstream according to the embodiments basicallyincludes a header and a payload.

The header is a V-PCC unit header according to embodiments, and containsatlas ID information that is a target of the unit.

The payload is a V-PCC unit payload according to embodiments, and maycontain data contained in the bitstream on a basis of a sample streamNAL unit.

For example, in the case of atlas data, an atlas (sub) bitstream iscontained in the payload as shown in FIG. 31.

The NAL unit data includes an atlas sequence parameter set, an atlasframe parameter set, an atlas tile group layer, and SEI.

The atlas frame parameter set (see FIG. 35) includes atlas frame tileinformation (see FIG. 36, etc.), and includes ID information on theatlas tile groups based on the number of atlas tile groups.

The atlas tile group layer (see FIG. 39, etc.) includes an atlas tilegroup header (FIG. 39) and atlas tile group data (FIG. 41).

The atlas tile group header contains the address of the atlas tile groupheader and the type of the atlas tile group header.

The bitstream is encapsulated in a file container by the fileencapsulator according to the embodiments. The structure of the filecontainer conforms to the ISO BMFF scheme.

The file according to the embodiments contains AtlasRelationBoxaccording to the embodiments in order to signal an atlas relation.

The AtlasRelationBox includes VPCCAtlasRelationRecord VPCCAtlas, anddelivers, as shown in FIG. 44, an atlas ID, the number of atlas tilegroups, atlas tile group IDs according to the number of atlas tilegroups, track group IDs according to the number of track groups.

The SampleGroupDescriptionBox of the file contains the start number forthe NAL units.

The method/device according to the embodiments may process an object ofdynamic point cloud data. That is, a signaling method for a bitstreamand file format for a dynamic point cloud object is provided.

For example, to support partial access of a dynamic point cloud object,atlas tile group information associated with some data of a V-PCC objectincluded in each spatial region of the point cloud object at the filesystem level may be provided.

Additionally, an extended signaling scheme for label and/or patchinformation included in each atlas tile group is provided.

FIGS. 53, 54, and 55 show scene object information according toembodiments.

FIGS. 53, 54, and 55 show scene object information contained in theV-PCC bitstream according to the embodiments of FIGS. 25 and 26.

FIGS. 53 to 58 illustrate information included in a volumetricannotation SEI message contained in a V-PCC bitstream according toembodiments.

An object according to the embodiments is a point cloud object.Furthermore, the object is a concept that includes even (partial)objects that constitute or divide the object.

The methods/devices according to the embodiments may provide partialaccess on a basis of a 3D spatial region including one or more sceneobjects based on scene object information according to the embodiments.

SEI messages according to the embodiments include information aboutprocesses related to decoding, reconstruction, display, or otherpurposes.

SEI messages according to the embodiments include two types: essentialand non-essential.

Non-essential SEI messages are not required by the decoding process.Decoders are not required to process this information for output orderconformance.

Volumetric annotation information (volumetric annotation SEI message)including scene object information, object label information, patchinformation, and volumetric rectangle information according toembodiments may be a non-essential SEI message.

According to embodiments, the above-mentioned information may be carriedin an essential SEI message.

Essential SEI messages are an integral part of the V-PCC bitstream andshould not be removed from the bitstream. The essential SEI messages maybe categorized into two types:

Type-A essential SEI messages: These SEIs may contain informationrequired to check bitstream conformance and for output timing decoderconformance. The V-PCC decoders according to the embodiments do notdiscard any relevant Type-A essential SEI messages. The V-PCC decoderaccording to the embodiments may consider such information for bitstreamconformance and for output timing decoder conformance.

Type-B essential SEI messages: V-PCC decoders that conform to aparticular reconstruction profile may not discard any relevant Type-Bessential SEI messages, and may consider the same for 3D point cloudreconstruction and conformance purposes.

FIG. 46 shows a volumetric annotation SEI message.

The V-PCC bitstream according to the embodiments defines volumetricannotation SEI messages that may be related to partial access as shownin FIG. 46.

soi_cancel_flag equal to 1 indicates that the scene object informationSEI message cancels the persistence of any previous scene objectinformation SEI message in output order.

soi_num_object_updates indicates the number of objects that are to beupdated by the current SEI.

When soi_num_object_updates is greater than 0, the following elementsmay be included in the scene object information.

soi_simple_objects_flag equal to 1 indicates that no additionalinformation for an updated or newly introduced object will be signaled.soi_simple_objects_flag equal to 0 indicates that additional informationfor an updated or newly introduced object may be signaled.

When soi_simple_objects_flag is equal to 0, the following elements maybe included in the scene object information.

If soi_simple_objects_flag is not equal to 0, flags may be set assoi_object_label_present_flag=0, soi_priority_present_flag=0,soi_object_hidden_present_flag=0, soi_object_dependency_present_flag=0,soi_visibility_cones_present_flag=0, soi_3d_bounding_box_present_flag=0,soi_collision_shape_present_flag=0, soi_point_style_present_flag=0,soi_material_idpresent_flag=0, and soi_extension_present_flag=0.

soi_object_label_present_flag equal to 1 indicates that object labelinformation is present in the current scene object information SEImessage. soi_object_label_present_flag equal to 0 indicates that objectlabel information is not present).

soi_priorit_ypresent_flag equal to 1 indicates that priority informationis present in the current scene object information SEI message.soi_priority_present_flag equal to 0 indicates that priority informationis not present.

soi_object_hidden_present_flag equal to 1 indicates that hidden objectinformation is present in the current scene object information SEImessage. soi_object_hidden_present_flag equal to 0 indicates that hiddenobject information is not present.

soi_object_dependency_present_flag equal to 1 indicates that objectdependency information is present in the current scene objectinformation SEI message. soi_object_dependency_present_flag equal to 0indicates that object dependency information is not present.

soi_visibility_cones_present_flag equal to 1 indicates that visibilitycones information is present in the current scene object information SEImessage. soi_visibility_cones_present_flag equal to 0 indicates thatvisibility cones information is not present.

soi_3d_bounding_box_present_flag equal to 1 indicates that 3D boundingbox information is present in the current scene object information SEImessage. soi_3d_bounding_box_present_flag equal to 0 indicates that 3Dbounding box information is not present.

soi_collision_shape_present_flag equal to 1 indicates that collisioninformation is present in the current scene object information SEImessage. soi_collision_shape_present_flag equal to 0 indicates thatcollision shape information is not present.

soi_point_style_present_flag equal to 1 indicates that point styleinformation is present in the current scene object information SEImessage. soi_point_style_present_flag equal to 0 indicates that pointstyle information is not present.

soi_material_idpresent_flag equal to 1 indicates that material IDinformation is present in the current scene object information SEImessage. soi_material_idpresent_flag equal to 0 indicates that materialID information is not present.

soi_extension_present_flag equal to 1 indicates that additionalextension information shall be present in the current scene objectinformation SEI message. soi_extension_present_flag equal to 0 indicatesthat additional extension information is not present. It is arequirement of bitstream conformance to this version of thespecification that soi_extension_present_flag shall be equal to 0.

When soi_3d_bounding_box_present_flag is equal to 1, the followingelements may be included in the scene object information.

soi_3d_bounding_box_scale_log 2 indicates the scale to be applied to the3D bounding box parameters that may be specified for an object.

soi_3d_bounding_box_precision_minus8 plus 8 indicates the precision ofthe 3D bounding box parameters that may be specified for an object.

soi_log 2_max_object_idx_updated specifies the number of bits used tosignal the value of an object index in the current scene objectinformation SEI message.

When soi_object_dependency_present_flag is equal to 1, the followingelements may be included in the scene object information.

soi_log 2_max_object_dependency_idx specifies the number of bits used tosignal the value of a dependency object index in the current sceneobject information SEI message.

The following elements as many as the soi_num_object_updates value maybe included in the scene object information.

soi_object_idx[i] indicates the object index of the i-th object to beupdated. The number of bits used to represent soi_object_idx[i] is equalto soi_log 2_max_object_idx_updated. When soi_object_idx[i] is notpresent in the bitstream, its value may be inferred to be equal to 0.

soi_object_cancel_flag[i] equal to 1 indicates that the object withindex equal to i may be canceled and that the variable ObjectTracked[i]shall be set to 0. Furthermore, all of its associated parameters,including the object label, 3D bounding box parameters, priorityinformation, hidden flag, dependency information, visibility cones,collision shapes, point style, and material id, may be reset to theirdefault values. shall also be set equal to 0. soi_object_cancel_flagequal to 0 indicates that the object with index equal tosoi_object_idx[i] shall be updated with information that follows thiselement and that that the variable ObjectTracked[i] may be set to 1.

When soi_object_cancel_flag[k] is not equal to 1 andsoi_object_label_present_flag is equal to 1, the following element maybe included in the scene object information.

soi object label update flag[i] equal to 1 indicates that object labelupdate information is present for an object with object index i. soiobject label update flag[i] equal to 0 indicates that object labelupdate information is not present.

When soi object label update flag[k] is equal to 1, the followingelement may be included in the scene object information.

soi_object_label_idx[i] indicates the label index of an object withindex i.

When soi_priority_present_flag is equal to 1, the following element maybe included in the scene object information.

soi_priority_update_flag[i] equal to 1 indicates that priority updateinformation is present for an object with object index i.soi_priority_update_flag[i] equal to 0 indicates that object priorityinformation is not present.

When soi_priority_update_flag[k] is equal to 1, the following elementmay be included in the scene object information.

soi_priority_value[i] indicates the priority of an object with index i.The lower the priority value, the higher the priority.

When soi_object_hidden_present_flag is 1, the following element may beincluded in the scene object information.

soi_object_hidden_flag[i] equal to 1 indicates that the object withindex i shall be hidden. soi_object_hidden_flag[i] equal to 0 indicatesthat the object with index i shall become present.

When soi_object_dependency_present_flag is equal to 1, the followingelement may be included in the scene object information.

soi_object_dependency_update_flag[i] equal to 1 indicates that objectdependency update information is present for an object with object indexi. soi_object_dependency_update_flag[i] equal to 0 indicates that objectdependency update information is not present.

When soi_object_dependency_update_flag[k] is equal to 1, the followingelement may be included in the scene object information.

soi_object_num_dependencies[i] indicates the number of dependencies ofobject with index i.

The following element may be included in the scene object informationaccording to the value of soi_object_num_dependencies[k].

soi_object_dependency_idx[i][j] indicates the index of the j-th objectthat has a dependency with the object with object index i.

When soi_visibility_cones_present_flag is equal to 1, the followingelement may be included in the scene object information.

soi_visibility_cones_update_flag[i] equal to 1 indicates that visibilitycones update information is present for an object with object index i.soi_visibility_cones_update_flag[i] equal to 0 indicates that visibilitycones update information is not present.

When soi_visibility_cones_update_flag[k] is equal to 1, the followingelements may be included in the scene object information.

soi_direction_x[i] indicates the normalized x-component value of thedirection vector for the visibility cone of an object with object indexi. The value of soi_direction_x[i], when not present, may be assumed tobe equal to 1.0.

soi_direction_y[i] indicates the normalized y-component value of thedirection vector for the visibility cone of an object with object indexi. The value of soi_direction_y[i], when not present, may be assumed tobe equal to 1.0.

soi_direction_z[i] indicates the normalized z-component value of thedirection vector for the visibility cone of an object with object indexi. The value of soi_direction_z[i], when not present, may be assumed tobe equal to 1.0.

soi_angle[i] indicates the angle of the visibility cone along thedirection vector in degrees. The value of soi_angle[i], when notpresent, may be assumed to be equal to 180°.

When soi_3d_bounding_box_present_flag is equal to 1, the followingelements may be included in the scene object information.

soi_3d_bounding_box_update_flag[i] equal to 1 indicates that 3D boundingbox information is present for an object with object index i.soi_3d_bounding_box_update_flag[i] equal to 0 indicates that 3D boundingbox information is not present.

soi_3d_bounding_box_x[i] indicates the x coordinate value of the originposition of the 3D bounding box of an object with index i. The defaultvalue of soi_3d_bounding_box_x[i] may be equal to 0.

soi_3d_bounding_box_y[i] indicates the y coordinate value of the originposition of the 3D bounding box of an object with index i. The defaultvalue of soi_3d_bounding_box_y[i] may be equal to 0.

soi_3d_bounding_box_z[i] indicates the z coordinate value of the originposition of the 3D bounding box of an object with index i. The defaultvalue of soi_3d_bounding_box_z[i] may be equal to 0.

soi_3d_bounding_box_delta_x[i] indicates the size of the bounding box onthe x axis of an object with index i. The default value ofsoi_3d_bounding_box_delta_x[i] may be equal to 0.

soi_3d_bounding_box_delta_y[i] indicates the size of the bounding box onthe y axis of an object with index i. The default value ofsoi_3d_bounding_box_delta_y[i] may be equal to 0.

soi_3d_bounding_box_delta_z[i] indicates the size of the bounding box onthe z axis of an object with index i. The default value ofsoi_3d_bounding_box_delta_z[i] may be equal to 0.

When soi_collision_shape_present_flag is equal to 1, the followingelements may be included in the scene object information.

soi_collision_shape_update_flag[i] equal to 1 indicates that collisionshape update information is present for an object with object index i.soi_collision_shape_update_flag[i] equal to 0 indicates that collisionshape update information is not present.

When soi_collision_shape_update_flag[k]] is equal to 1, the followingelement may be included in the scene object information.

soi_collision_shape_id[i] indicates the collision shape id of an objectwith index i.

When soi_point_style_present_flag is equal to 1, the following elementsmay be included in the scene object information.

soi_point_style_update_flag[i] equal to 1 indicates that point styleupdate information is present for an object with object index i.soi_point_style_update_flag[i] equal to 0 indicates that point styleupdate information is not present.

When soi_point_style_update_flag[k]] is equal to 1, the followingelements may be included in the scene object information.

soi_point_shape_id[i] indicates the point shape id of an object withindex i. The default value of soi_point_shape_id[i] may be equal to 0.

soi_point_size[i] indicates the point size of an object with index i.The default value of soi_point_size[i] may be equal to 1.

When soi_material_idpresent_flag is equal to 1, the following elementsmay be included in the scene object information.

soi_material_id_update_flag[i] equal to 1 indicates that material IDupdate information is present for an object with object index i.soi_point_style_update_flag[i] equal to 0 indicates that point styleupdate information is not present.

When soi_material_id_update_flag[k] is equal to 1, the following elementmay be included in the scene object information.

soi_material_id[i] indicates the material ID of an object with index i.The default value of soi_material_id[i] may be equal to 0.

FIG. 56 shows object label information according to embodiments.

oli_cancel_flag equal to 1 indicates that the object label informationSEI message cancels the persistence of any previous object labelinformation SEI message in output order.

When oli_cancel_flag is not equal to 1, the following elements may beincluded in the object label information.

oli_label_language_present_flag equal to 1 indicates that label languageinformation is present in the object label information SEI message.oli_label_language_present_flag equal to 0 indicates that label languageinformation is not present.

When oli_label_language_present_flag is equal to 1, the followingelements may be included in the object label information.

oli_bit_equal_to_zero may be equal to 0.

oli_label_language contains a language tag as specified by IETF RFC 5646followed by a null termination byte equal to 0x00. The length of theoli_label_language syntax element may be less than or equal to 255bytes, not including the null termination byte.

oli_num_label updates indicates the number of labels that are to beupdated by the current SEI.

The following elements may be included in the object label informationas many as the value of oli_num_label updates.

oli_label_idx[i] indicates the label index of the i-th label to beupdated.

oli_label_cancel_flag equal to 1 indicates that the label with indexequal to oli_label_idx[i] shall be canceled and set equal to an emptystring. oli_label_cancel_flag equal to 0 indicates that the label withindex equal to oli_label_idx[i] shall be updated with information thatfollows this element.

When oli_label_cancel_flag is not equal to 1, the following elements maybe included in the object label information.

oli_bit_equal_to_zero is equal to 0.

oli_label[i] indicates the label of the i-th label. The length of thevti_label[i] syntax element shall be less than or equal to 255 bytes,not including the null termination byte.

FIG. 57 shows patch information according to embodiments.

pi_cancel_flag equal to 1 indicates that the patch information SEImessage cancels the persistence of any previous patch information SEImessage in output order and that all entries in the patch informationtable shall be removed.

pi_num_tile_group_updates indicates the number of tile groups that areto be updated in the patch information table by the current SEI message.

When pi_num_tile_group_updates is greater than 0, the following elementsmay be included in the patch information.

pi_log 2_max_object_idx_tracked specifies the number of bits used tosignal the value of a tracked object index in the current patchinformation SEI message.

pi_log 2_max_patch_idx_updated specifies the number of bits used tosignal the value of an updated patch index in the current patchinformation SEI message.

The following elements as many as the pi_num_tile_group_updates valuemay be included in the patch information.

pi_tile_group_address[i] specifies the tile group address for the i-thupdated tile group in the current SEI message.

pi_tile_group_cancel_flag[i] equal to 1 indicates that the tile groupwith index i shall be reseted and all patches previously assigned tothis tile group will be removed. pi_tile_group_cancel_flag[i] equal to 0indicates that all patches previously assigned to the tile group willindex i will be retained.

pi_num_patch_updates[i] indicates the number of patches that are to beupdated by the current SEI within the tile group with index i in thepatch information table.

The following elements as many as the pi_num_patch_updates value may beincluded in the patch information.

pi_patch_idx[i][j] indicates the patch index of the j-th patch in tilegroup with index i that is to be updated in the patch information table.The number of bits used to represent pi_patch_idx[i] is equal to pi_log2_max_patch_idx_updated. When pi_patch_idx[i] is not present in thebitstream, its value may be inferred to be equal to 0.

pi_patch_cancel_flag[i][j] equal to 1 indicates that the patch withindex j in tile group with index i shall be removed from the patchinformation table.

When pi_patch_cancel_flag[j][p] is not equal to 1, the followingelements may be included in the patch information.

pi_patch_number_of_objects_minus1[i][j] indicates the number of objectsthat are to be associated with the patch with index j in tile group withindex i.

m may be set as m=pi_patch_number_of_objects_minus1[j][p]+1, and thefollowing element as many as the value of m may be included in the patchinformation.

pi_patch_object_idx[i][j][k] indicates the k-th object index that isassociated with the j-th patch in tile group with index i. The number ofbits used to represent pi_patch_object_idx[i] may be equal to pi_log2_max_object_idx_tracked. When pi_patch_object_idx[i] is not present inthe bitstream, its value may be inferred to be equal to 0.

FIG. 58 shows volumetric rectangle information according to embodiments.

vri_cancel_flag equal to 1 indicates that the volumetric rectanglesinformation SEI message cancels the persistence of any previousvolumetric rectangles information SEI message in output order and thatall entries in the volumetric rectangle information table shall beremoved.

vri_num_rectangles_updates indicates the number of volumetric rectanglesthat are to be updated by the current SEI.

When vri_num_rectangles_updates is greater than 0, the followingelements may be included in the volumetric rectangle information.

vri_log 2_max_object_idx_tracked specifies the number of bits used tosignal the value of a tracked object index in the current volumetricrectangle information SEI message.

vri_log 2_max_rectangle_idx_updated specifies the number of bits used tosignal the value of an updated volumetric rectangle index in the currentvolumetric rectangle information SEI message.

The following elements as many as the value ofvri_num_rectangles_updates may be included in the volumetric rectangleinformation.

vri_rectangle_idx[i]] indicates the i-th volumetric rectangle index thatis to be updated in the volumetric rectangle information table. Thenumber of bits used to represent vri_rectangle_idx[i] may be equal tovri_log 2_max_rectangle_idx_updated. When vri_rectangle_idx[i] is notpresent in the bitstream, its value may be inferred to be equal to 0.

vri_rectangle_cancel_flag[i] equal to 1 indicates that the volumetricrectangle with index i may be removed from the volumetric rectangleinformation table.

When vri_rectangle_cancel_flag[p] is not equal to 1, the followingelements may be included in the volumetric rectangle information.

vri_bounding_box_update_flag[i] equal to 1 indicates that 2D boundingbox information for the volumetric rectangle with index i should beupdated. vti_bounding_box_update_flag[i] equal to 0 indicates that 2Dbounding box information for the volumetric rectangle with index ishould not be updated.

When vri_bounding_box_update_flag[p] is equal to 1, the followingelements may be included in the volumetric rectangle information.

vri_bounding_box_top[i] indicates the vertical coordinate value of thetop-left position of the bounding box of the i-th volumetric rectanglewithin the current atlas frame. The default value ofvri_bounding_box_top[i] may be equal to 0.

vri_bounding_box_left[i] indicates the horizontal coordinate value ofthe top-left position of the bounding box of the i-th volumetricrectangle within the current atlas frame. The default value ofvri_bounding_box_left[i] may be equal to 0.

vri_bounding_box_width[i] indicates the width of the bounding box of thei-th volumetric rectangle. The default value ofvri_bounding_box_width[i] may be equal to 0.

vri_bounding_box_height[i] indicates the height of the bounding box ofthe i-th volumetric rectangle. The default value ofvri_bounding_box_height[i] may be equal to 0.

vri_rectangle_number_of_objects_minus1[i] indicates the number ofobjects that are to be associated with the i-th volumetric rectangle.

The value of m may be set tovri_rectangle_number_of_objects_minus1[p]+1. For the value of m, thefollowing element may be included in the volumetric rectangleinformation.

vri_rectangle_object_idx[i][j] indicates the j-th object index that isassociated with the i-th volumetric rectangle. The number of bits usedto represent vri_rectangle_object_idx[i] may be equal to vri_log2_max_object_idx_tracked. When vri_rectangle_object_idx[i] is notpresent in the bitstream, its value may be inferred to be equal to 0.

FIG. 59 shows hierarchy of an SEI message in an atlas sub-bitstreamaccording to embodiments.

The transmission method/device according to the embodiments may generatean atlas sub-bitstream as shown in FIG. 59.

A relationship between the NAL unit data constituting the atlassub-bitstream is established.

In SEI messages added to the atlas sub-bitstream, informationcorresponding to volumetric_tiling_info_objects( ) isscene_object_information( ). There are patch_information( ) which mayindicate the relationship with objects belonging to respective patches,and volumetric_rectangle_information( ) which may be allocated for oneor more objects.

The bitstream 59000 corresponds to the bitstream 25000 of FIG. 25.

The NAL unit 59010, which is contained in the payload of the v-pcc unitcontained in the atlas data of the bitstream 59000, corresponds to thebitstream of FIG. 31.

The atlas frame parameter set 59020 of FIG. 59 corresponds to the atlasframe parameter set of FIG. 35.

The atlas tile group (or tile) layer 59030 of FIG. 59 corresponds to theatlas tile group (or tile) layer of FIG. 40.

The SEI message 59040 of FIG. 59 corresponds to the SEI messages of FIG.31.

The atlas frame tile information 59050 of FIG. 59 corresponds to theatlas frame tile information of FIG. 37.

The atlas tile group (or tile) header 59060 of FIG. 59 corresponds tothe atlas tile group (or tile) header of FIG. 39.

The scene object information 59070 of FIG. 59 corresponds to the sceneobject information of FIGS. 53 to 55.

The object label information 59080 of FIG. 59 corresponds to the objectlabel information of FIG. 56.

The patch information 59090 of FIG. 59 corresponds to the patchinformation of FIG. 57.

The volumetric rectangle information 59100 of FIG. 59 corresponds to thevolumetric rectangle information of FIG. 58.

The atlas frame tile information 59050 may be identified by an atlastile group (or tile) ID, and may be included in the atlas frameparameter set 59020.

The atlas tile group (or tile) layer 59030 may include an atlas tilegroup (or tile) header 59060. The atlas tile group (or tile) header maybe identified by an atlas tile group (or tile) address.

The scene object information 59070 may be identified by an object indexand an object label index.

The object label information 59080 may be identified by a label index.

The patch information 59090 may be identified by a tile group (or tile)address and a patch object index.

The volumetric rectangle information 59100 may be identified by arectangle object index.

The transmission method/device according to the embodiments may generatea bitstream by encoding point cloud data and generatingreference/hierarchical relationship information as shown in FIG. 59.

The reception method/device according to the embodiments may receive abitstream as shown in FIG. 59 and restore point cloud data contained inthe bitstream. In addition, it may efficiently decode and restore pointcloud data based on the atlas data of FIG. 59 contained in thebitstream.

FIG. 60 illustrates a configuration of an atlas tile group (or tile)according to embodiments.

FIG. 60 illustrates a relationship between a video frame, an atlas, apatch, and an object for point cloud data presented and signaled in abitstream by the methods/devices according to the embodiments.

An atlas frame may be generated and decoded by the metadata processors18005 and 19002 of the transmission device and reception deviceaccording to the embodiments. Thereafter, the atlas bitstreamrepresenting the atlas frame may be formed in a format according toembodiments and transmitted/received by the encapsulator/decapsulator20004, 20005, 21009, 22000 of the transmission device/reception deviceaccording to the embodiments.

An object is a target expressed as point cloud data.

According to embodiments, the location and/or size of objects may changedynamically. In this case, a configuration of a changing atlas tilegroup or atlas tile may be given as shown in FIG. 59.

Patches P1 to P3 may be configured with multiple scene objects O1 to O2constituting one or more objects. Frame 1 (video frame 1) may becomposed of three atlas tile groups.

An atlas tile group according to embodiments may be referred to as anatlas tile. Atlas tile groups 1 to 3 may correspond to atlas tiles 1 to3.

Atlas tile group 1 may include 3 patches. Patch 1 (P1) may include threeobjects O1 to O3. Patch 2 (P2) may contain one object (O2). Patch 3 (P3)may contain one object O1.

The methods/devices according to the embodiments may express a mappingrelationship between patches and objects based on a field(pi_patch_object_idx[j]) corresponding to an object ID included in thepatch information (patch_information( ) in FIG. 57).

Atlas tile group (or tile) 2 may include two patches P1 and P2. Patch 1(P1) may contain one object O1, and patch 2 (P2) may contain two objectsO2.

The methods/devices according to the embodiments may express a mappingrelationship based on the field (pi_patch_object_idx[j]) correspondingto an object ID included in the patch information (patch_information inFIG. 57).

Atlas tile group (or tile) 3 may include three patches P1, P2, and P3.Patch 1 (P1) may contain one object O2.

The methods/devices according to the embodiments may indicate a mappingrelationship based on the field (pi_patch_object_idx[j]) correspondingto an object ID included in the patch information (patch information inFIG. 57).

Frame 2 may be composed of three atlas tile groups (or tiles).

Atlas tile group (or tile) 1 (49000) may include two patches P1 and P2.Patch 1 may contain two objects O1 and 02. Patch 2 may contain oneobject O1.

The methods/devices according to the embodiments may indicate a mappingrelationship based on the field (pi_patch_object_idx[j]) correspondingto an object ID included in the patch information (patch_information inFIG. 57).

Atlas tile group (or tile) 2 (49000) may include two patches P1 and P2.Patch 1 (P1) may contain one object (O2). Patch 2 (P1) may contain twoobjects.

The methods/devices according to the embodiments may indicate a mappingrelationship based on the field (pi_patch_object_idx[j]) correspondingto an object ID included in the patch information (patch_information inFIG. 57).

Atlas tile group (or tile) 3 may include two patches P1 and P2. Patch 1(P1) may contain one object O1.

The methods/devices according to the embodiments may indicate a mappingrelationship based on the field (pi_patch_object_idx[j]) correspondingto an object ID included in the patch information (patch_information inFIG. 57).

A structure of data generated and transmitted/received by a V-PCC (V3C)system included in or connected to the point cloud datatransmission/reception method/device according to embodiments will bedescribed.

The methods/devices according to the corresponding embodiments maygenerate a file, and generate and transmit/receive the following data inthe file.

The transmission method/device according to the embodiments may generateand transmit the following data structures based on a bitstreamcontaining encoded point cloud data, and the reception method/deviceaccording to the embodiments may receive and parse the following datastructures, and restore the point cloud data contained in the bitstream.

FIG. 61 shows a VPCC spatial regions box according to embodiments.

A file generated and transmitted/received by the point cloud datatransmission/reception device according to the embodiments and a systemincluded in or connected to the transmission/reception device include aVPCC Spatial Regions Box.

This box may contain information such as 3D bounding box informationabout VPCC spatial regions and label information related to the spatialregions, an atlas type group ID (or atlas tile ID), and a patch ID thatmay be included in an atlas tile group (or tile).

In addition, this box may contain V-PCC component track groupinformation related to the spatial regions. The V-PCC spatial regionsbox may be included in the sample entry of the V-PCC track.

FIGS. 61 and 62 show common data structures that may be included in atrack of a file (or item) according to embodiments, and are included inthe track.

FIG. 61 shows signaling information for processing a spatial region ofpoint cloud data.

3d_region_id is an identifier for the spatial region.

x, y, and z specify the x, y, and z coordinate values, respectively, ofa 3D point in the coordinate system.

cuboid_dx, cuboid_dy, and cuboid_dz_indicate the dimensions of thecuboid sub-region in the coordinate system along the x, y, and z axes,respectively, relative to an anchor point.

An anchor is a 3D point in the coordinate system used as the anchor forthe 3D spatial region.

dimensions_included_flag is a flag that indicates whether the dimensionsof the spatial region are signaled.

According to the embodiments, methods/devices may process a sub-regionof the point cloud based on the information of FIG. 61, and thereception device may provide partial access to the point cloud.

FIG. 62 shows a VPCC spatial regions box according to embodiments.

num_atlas indicates the number of atlases associated with spatialregions indicated by 3D SpatialRegionStruct.

atlas_id is an identifier of the associated atlas sub-bitstream.

num_regions indicates the number of 3D spatial regions in the pointcloud.

num_region_tile groups may indicate the number of atlas tile groups inan atlas substream associated with some data of the V-PCC objectincluded in the spatial region.

atlas tile group may be interpreted as the same meaning of atlas tile inaccordance with some embodiments. In accordance with embodiments, atlastile group and atlas tile has the same meaning and are compatible witheach other.

region_tile_group_id may indicate the id of an atlas tile group in anatlas substream associated with some data of a V-PCC object included inthe spatial region.

num_patch updates may indicate the number of patches belonging to anatlas tile group associated with some data of the V-PCC object includedin the corresponding spatial region among the patches of each atlas tilegroup.

patch_id may indicate patch ids of patches belonging to the atlas tilegroup associated with some data of the V-PCC object included in thecorresponding spatial region among the patches of each atlas tile group.

num_track_groups indicates the number of track groups associated with a3D spatial region. A track in accordance with embodiments indicates atrack carrying a V-PCC component.

track_group_id indicates the track group of tracks which carry the V-PCCcomponents for the associated 3D spatial region.

label_id may indicate a label id related to an atlas tile groupassociated with some data of a V-PCC object included in a correspondingspatial region.

label_language may indicate language information about a label relatedto an atlas tile group associated with some data of a V-PCC objectincluded in a corresponding spatial region.

label_name may indicate label name information related to an atlas tilegroup associated with some data of a V-PCC object included in acorresponding spatial region.

The method/device according to the embodiments may include a dynamicspatial region sample group for signaling a dynamic spatial region in afile.

The ‘dysr’ grouping_type for sample grouping represents the assignmentof samples in a V-PCC track to spatial region box carried in this samplegroup. When SampleToGroupBox with grouping_type equal to ‘dysr’ ispresent, SampleGroupDescriptionBox with the same grouping type ispresent, and contains the ID of this group to which the samples belong.

A V-PCC track may contain SampleToGroupBox with grouping_type equal to‘dysr’.

aligned(8) class Dynamic3DspatialRegionSampleGroupDescriptionEntry( )extends SampleGroupDescriptionEntry(‘dysr’) { VPCCSpatialRegionsBox( );}

The methods/devices according to the embodiments may generate a timedmetadata track and transmit/receive based on a file (or item) container.

According to embodiments, the dynamic spatial region may be added byconfiguring a timed metadata track as follows.

If the V-PCC track has an associated timed-metadata track with a sampleentry type ‘dysr’, spatial regions defined for the point cloud streamcarried by the V-PCC track may be dynamic regions.

The associated timed-metadata track may contain a ‘cdsc’ track referenceto the V-PCC track carrying the atlas stream.

The method/device according to the embodiments may generate thefollowing information in the sample entry for the dynamic spatialregion.

Sample Entry

aligned(8) class DynamicSpatialRegionSampleEntry extendsMetaDataSampleEntry(‘dysr’) { VPCCSpatialRegionsBox( ); }

Sample Format

aligned(8) class DynamicSpatialRegionSample( ) { unsigned int(16)num_regions; for(i=0; i<num_regions; i++) { 3DspatialRegionStruct(1);LabelInfoStruct( ); unsigned int(16) num_atlas; for(m=0; m< num_atlas ;m++) { unsigned int(16) atlas_id; unsigned int(16)num_region_tile_groups; for (k=0; k < num_region_tile_groups; k++) {unsigned int(16) region_tile_group_id; unsigned int(8)num_patch_updates; for (p=0; p < num_patch_updates; p++) unsignedint(16) patch_id; } } unsigned int(8) num_track_groups; for (j=0; j <num_track_groups; j++) { unsigned int(32) track_group_id; } } }

In order to process the spatial region, an atlas ID may indicate one ormore atlases associated with each region.

A track of a file in accordance with embodiments may include spatialregion information including one or more atlas tile identifierinformation for a spatial region of point cloud data.

FIGS. 63, 64, and 65 are flowcharts illustrating file encapsulationaccording to embodiments.

FIGS. 64 and 65 illustrate the operation of the file encapsulators10003, 20004, and 21009.

The point cloud data transmission device and the encapsulator accordingto the embodiments may configure a V-PCC bitstream in the isobmff fileformat, and create a box structure necessary for encoding in the isobmfffile format. The transmitter may transmit the generated data.

In addition, the point cloud data transmission device according to theembodiments, for example, the file/segment encapsulator, etc. may createand transmit the aforementioned VPCC spatial regions box.

0. The encapsulator receives a V-PCC encoded bitstream (FIGS. 25 and26).

1. The encapsulator may create a V-PCC track in ISOBMFF file.

1-1. The encapsulator may create a timed-metadata track for a dynamicspatial region.

2. A sample entry may be created in the V-PCC track created in operation1 above.

3. The encapsulator may acquire VPS (VPCC Parameter Set) informationfrom the input bitstream (FIGS. 25 and 26).

4. The encapsulator may add the VPS information to the sample entry.

5. The encapsulator may acquire atlas scene object information (FIG. 53or the like) from the input bitstream (FIGS. 25 and 26).

5-1. The encapsulator may acquire atlas object label information (FIG.56) from the input bitstream (FIGS. 25 and 26).

5-2. The encapsulator may acquire atlas patch information (FIG. 57) fromthe input bitstream (FIGS. 25 and 26).

6. The encapsulator may generate a VPCCSpatialRegionsBox structure (FIG.61, etc.) according to embodiments suitable for the point cloud systemfile format based on the atlas volumetric tiling information (FIG. 36,FIG. 39, FIG. 41, FIG. 57, etc.) and add the same to the sample entry.

Also, for the dynamic spatial region, the VPCCSpatialRegionsBoxstructure may be added to the sample entry of the timed-metadata track.

7. The encapsulator may acquire atlas VPCC unit header info (FIG. 26,etc.) from the input bitstream.

8. The encapsulator may add VPCC unit header info to the sample entry.

9. The encapsulator may add atlas NAL unit data (FIG. 31, etc.) to asample entry or sample according to nalType.

10. The encapsulator may add data except for NAL_ASPS or NAL_XXXX_SEI,which is an atlas NAL unit data type to a sample.

11. The encapsulator may add the sample created in operation 10 above tothe V-PCC track.

12. The encapsulator may add DynamicSpatialRegionSample according toembodiments for the dynamic spatial region to a sample of thetimed-metadata track.

FIGS. 66 and 67 are flowcharts illustrating an operation of a filedecapsulator according to embodiments.

The point cloud data reception device according to the embodiments mayinclude a receiver and/or a file/segment decapsulator (which may bereferred to as a decapsulator). The receiver may receive point clouddata (in the V-PCC isobmff file format). The decapsulator maydecapsulate the V-PCC isobmff file into a V-PCC bitstream, and may parsea box structure or the like required for decoding thereof. The receptiondevice may further include a decoder. The decoder may decode the V-PCCbitstream.

In addition, the point cloud data reception device according to theembodiments, for example, the file/segment decapsulator and the like mayreceive and parse the VPCC spatial regions box according to theembodiments.

0. The decapsulator receives a file encapsulated in V-PCC Isobmff.

1. The decapsulator may acquire VPS (V-PCC Parameter Set) informationfrom the sample entry of the input isobmff file.

2. The decapsulator may configure the VPS information acquired inoperation 1 above in the form of a V-PCC bitstream.

3. The decapsulator may acquire V-PCC unit header information from thesample entry of the input isobmff file.

4. The decapsulator may configure the V-PCC unit header informationacquired in operation 3 above in the form of a V-PCC bitstream.

5. The decapsulator may acquire VPCCSpatialRegionsBox information fromthe sample entry of the input isobmff file. In addition,VPCCSpatialRegionsBox information may be acquired from the sample entryof the timed-metadata track for a dynamic spatial region.

6. The decapsulator may acquire V-PCC configuration information from thesample entry of the input isobmff file. The V-PCC configurationinformation includes VPS and atlas data in which NAL unit type isNAL_ASPS or NAL_XXXX_SEI.

7. The decapsulator may acquire atlas data such having the NAL unit typesuch as TSA from the sample of the input isobmff file.

7-1. The decapsulator may acquire DynamicSpatialRegionSample informationfrom a sample of the timed-metadata track for the dynamic spatialregion.

8. The decapsulator may parse only data having the matchingafti_tile_group_id and atgh_address among the atlas data acquired inoperation 7, based on vti_object_tile_group_id acquired in operation 5above.

9. The decapsulator may configure SampleStreamNalUnit data constitutingthe V-PCC atlas sub-bitstream using the atlas data acquired inoperations 6 to 8 above.

10. The decapsulator may configure a V-PCC atlas sub-bitstream for V-PCCbitstream decoding.

11. The decapsulator may acquire an atlas tile group and patch data forreconstructing a point cloud by parsing the V-PCC atlas sub-bitstreamgenerated in operation 10 above through VPCCBitstreamDecoder.

FIG. 68 illustrates file level signaling according to embodiments.

The point cloud data transmission/reception method/device and the systemincluded in the transmission/reception device according to theembodiments may create and transmit/receive a file in a structure asshown in FIG. 68.

The point cloud data transmission/reception method/device and the systemincluded in the transmission/reception device according to theembodiments may signal data at the file level as follows.

Signaling information, metadata, parameters, etc. according toembodiments may be contained in the sample entry of the V-PCC track (orV3C track) 68030, and may be transmitted/received in the sample entryand the sample of the timed metadata track.

The V-PCC bitstream composed of a plurality of atlas tile groups (oratlas tiles) for partial access may be encapsulated by the encapsulatorin a file format structure as shown in FIG. 68. Sample group 155900 mayhave three atlas tile groups (corresponding to atlas tiles) (ATG1 toATG3, or AT1 to AT3).

Sample group 2 (68010) may have two atlas tile groups (or atlas tiles)due to changes in the position and/or size of spatial regions (ATG1 andATG2, or AT1 and AT2).

Sample group 3 (68020) may be composed of the same or different atlastile groups (or atlas tiles).

The file may contain a moov box and a mdat box. The moov box and themdat box may be referred to as tracks. When the type of the v-pcc track68030 is atlas data AD, the mdat box containing an atlas tilecorresponding to a sample may be positioned behind the moov box.

When there are multiple tracks in a file, grouping between tracks may beperformed.

A track containing OVD, a track containing GVD, and a track containingAVD may be grouped into track group 1 (68040).

A track containing GVD and a track containing AVD may be grouped intotrack group 2 (68050).

Referencing may be performed between tracks related to the file.

Track 1 (68030) may reference group 1 (68040) and group 2 (68050).

FIG. 69 illustrates file level signaling according to embodiments.

The method/device according to the embodiments may generate aNALUMapEntry as a SampleGroupEntry of SampleGroupDescription.

An atlas_tile_group_id (or atlas_tile_id) may be assigned to each atlasNAL unit. The point cloud receiver may aggregate only atlas NAL unitscorresponding to the respective spatial regions according to theatlas_tile_group_id (or atlas_tile_id).

As shown in FIG. 69, the method/device according to the embodiments maycreate a link relationship between sampletogroupbox and NALUMapEntry.Both sampletogroupbox and NALUMapEntry may be contained in the sampleentry in the moov box.

NALUMapEntry according to the embodiments may be defined as specified inISO/IEC 14496-15 [14496-15].

NALUMapEntry may be present in the V-PCC track whenVPCCSpatialRegionsBox is present.

The NALUMapEntry may be used to assign a groupID to each atlas NAL unit.

The NALUMapEntry may or may not be linked to a sample group descriptionsetting the grouping_type_parameter of the SampleToGroupBox of type‘nalm’.

A SampleToGroupBox of type ‘nalm’ may or may not use version 0 of thebox.

The V-PCC track according to the embodiments may containSampleToGroupBox 58000.

The SampleToGroupBox 69000 may contain the grouping_type_parameterhaving the value of nalm, and contain a plurality of sample groups.

Sample group 1 (68000), for example, when configured as shown in FIG.69, has sample_count set to 3 and includes samples 1 to 3. In this case,the sample description index may be 1.

Sample group 2 (69010) has sample_count set to 2, and may include sample1 and sample 2 as shown in FIG. 57. In this case, the sample descriptionindex is 2.

Sample group 3 (69020) has sample_count set to N and may include Nsamples. In this case, the sample description index is 3.

The V-PCC track according to the embodiments may contain aSampleGroupDescriptionBox 69010.

The SampleGroupDescriptionBox 69010 may contain additional informationabout the SampleToGroupBox. The grouping type is ‘nalm’, and file levelsignaling information may be provided for each sample group through asample group entry.

NALUMapEntry 1 (69020) may provide configuration information aboutsample group 1 (69000).

For example, when the configuration as shown in FIG. 57 is signaled,NALUMapEntry 1 (69020) may have 9 entries in total.

The NALUMapEntry may represent an atlas tile group (or atlas tile)included in NALUs 1-9 contained in the track related to sample group 1.

For example, NALUMapEntry 1 (69020) informs that NALU 1 is mapped toatlas tile group 1. Similarly, it informs that NALU 2 to 9 are matchedwith atlas tile groups 2 to 9, respectively.

The methods/devices according to the embodiments may provide thefollowing effects.

For example, a transmitter or receiver for providing a point cloudcontent service may configure a V-PCC bitstream and efficiently store afile.

V-PCC bitstreams may be effectively multiplexed. Efficient access to thebitstream may be supported on a V-PCC unit basis at the receiving side.The atlas stream of the V-PCC bitstream may be effective stored andtransmitted in tracks in the file. Efficient signaling of the atlas mayenable the reception device to perform efficient processing and partialaccess of point cloud data.

SEI messages/information for data processing and rendering in the V-PCCbitstream may be effectively stored and transmitted in a file.

The point cloud compression processing device, transmitter, receiver,point cloud player, encoder or decoder provides these effects.

The data representation/storage/signaling/encoding method according toembodiments may enable efficient access to a point cloud bitstream. Inaddition, it may enable effective access to the information necessaryfor data processing and rendering of the point cloud bitstream.

The transmitter or receiver according to the embodiments may efficientlystore and transmit the file of the point cloud bitstream through atechnique and signaling for partitioning and storing the V-PCC bitstreaminto one or more tracks in a file, signaling for indicating therelationship between the stored V-PCC bitstream and multiple tracks, andidentification of alternative V-PCC tracks stored in the file, and thelike.

FIG. 70 shows an encapsulated V-PCC data container structure accordingto embodiments.

he point cloud video encoder 10002 of the transmission device 10000 ofFIG. 1, the encoders of FIGS. 4 and 15, the transmission device of FIG.18, the video/image encoders 20002 and 20003 of FIG. 29, the processorand the encoders 21000 to 21008 of FIG. 21, and the XR device 2330 ofFIG. 23 generate a bitstream containing point cloud data according toembodiments.

The file/segment encapsulator 10003 of FIG. 1, the file/segmentencapsulator 20004 of FIG. 20, the file/segment encapsulator 21009 ofFIG. 21, and the XR device of FIG. 23 format the bitstream in the filestructure of FIGS. 24 and 25.

Similarly, the file/segment decapsulation module 10007 of the receptiondevice 10005 of FIG. 1, the file/segment decapsulators 20005, 21009, and22000 of FIGS. 20 to 23, and the XR device 2330 of FIG. 23 receive anddecapsulate a file and parse the bitstream. The bitstream is decoded bythe point cloud video decoder 10008 of FIG. 1, the decoders of FIGS. 16and 17, the reception device of FIG. 19, the video/image decoders 20006,21007, 21008, 22001, and 22002 of FIGS. 20 to 23, and the XR device 2330of FIG. 23 to restore the point cloud data.

FIGS. 70 and 71 show the structure of a point cloud data containeraccording to the ISOBMFF file format.

FIGS. 70 and 71 show the structure of a container for delivering pointclouds based on multiple tracks.

The methods/devices according to the embodiments may transmit/receive acontainer file in which point cloud data and additional data related tothe point cloud data are included based on multiple tracks.

Track-1 70000 is an attribute track, and may contain attribute data70040 encoded as illustrated in FIGS. 1, 4, 15, 18, and the like.

Track-2 70010 is an occupancy track, and may contain geometry data 70050encoded as illustrated in FIGS. 1, 4, 15, 18, and the like.

Track-3 70020 is a geometry track, and may contain occupancy data 70060encoded as illustrated in FIGS. 1, 4, 15, 18, and the like.

Track-4 70030 is a v-pcc (v3c) track, and may contain an atlas bitstream27070 containing data related to point cloud data.

Each track is composed of a sample entry and a sample. The sample is aunit corresponding to a frame. In order to decode the N-th frame, asample or sample entry corresponding to the N-th frame is required. Thesample entry may contain information describing the sample.

FIG. 71 shows a structure of a file according to embodiments.

The v3c track 71000 corresponds to track-4 70030. Data contained in thev3c track 71000 may have a format of a data container referred to as abox. The v3c track 71000 contains reference information about the V3Ccomponent tracks 71010 to 71030.

The reception method/device according to the embodiments may receive acontainer (which may be referred to as a file) containing point clouddata as shown in FIG. 71 and parse the V3C track, and may decode andreconstruct occupancy data, geometry data, and attribute data based onthe reference information contained in the V3C track.

The occupancy track 71010 corresponds to track-2 70010 and containsoccupancy data. The geometry track 71020 corresponds to track-3 70020and contains geometry data. The attribute track 71030 corresponds totrack-1 70000 and contains attribute data.

FIG. 72 shows tracks according to the embodiments.

The file according to the embodiments may contain one or more tracks asshown in FIG. 72.

Track 1 is an atlas track and may carry an atlas bitstream. Track 1 isan entry point and serves as an entry point for point cloud data in thefile.

When there are multiple tracks, Track 1 has a track reference. Forexample, based on v3v0 (occupancy data), v3va (attribute data), and v3vg(geometry data), access to each point cloud data may be performed.

Track 1 may include a sample entry and samples. The sample entry is V3Cconfiguration information according to embodiments, and may includeparameter sets and SEI information. The sample may contain atlas data.

Track 2 is a video component track carrying a geometry bitstream. Track2 contains a sample entry and samples. The sample entry is videoconfiguration information, and may include parameter sets, SEIinformation and include a V3C unit header. The samples may carrygeometry data.

Track 3 is a video component track carrying an attribute bitstream.Track 3 contains a sample entry and samples. The sample entry is videoconfiguration information, and may include parameter sets and SEIinformation, and include a V3C unit header. The samples may carryattribute data.

Track 4 is a video component track carrying an occupancy bitstream.Track 4 contains a sample entry and samples. The sample entry is videoconfiguration information, and may include parameter sets and SEIinformation, and include a V3C unit header. The samples may carryoccupancy data.

The methods/devices according to the embodiments may transmit andreceive volumetric visual data for point cloud data according to theembodiments based on the tracks of FIG. 72.

FIG. 73 illustrates a method of transmitting point cloud data accordingto embodiments.

S7300: the point cloud data transmission method according to theembodiments may include encoding the point cloud data.

The encoding operation according to the embodiments is performed asdescribed above regarding the transmission device 10000 of FIG. 1, theencoding process of FIG. 4, the operation of the encoder of FIG. 15, thetransmission device of FIG. 18, the encoding (20001, 20002, 20003) ofFIG. 20, preprocessing encoding (21001 to 21008) of FIG. 21, theoperation of the device of FIG. 23, generation of bitstreams of FIGS.25, 26, 59, and the like.

S7310: the point cloud data transmission method according to theembodiments may further include encapsulating a bitstream containing thepoint cloud data into a file.

The encapsulation operation according to the embodiments is performed asdescribed above regarding the operations of the file/segmentencapsulator 10003 of FIG. 1, the file/segment encapsulator 20004 ofFIG. 20, and the file/segment encapsulator 21009 of FIG. 21, the deviceof FIG. 23, file generation in FIGS. 52 and 68 to 72, and the like.

S7320: the point cloud data transmission method according to theembodiments may further include transmitting the point cloud data.

The transmission operation according to the embodiments is the same asdescribed above regarding the operation of the transmitter 10004 of FIG.1 and the like.

FIG. 74 illustrates a method of receiving point cloud data according toembodiments.

S7400: the method of receiving point cloud data according to theembodiments may include receiving a bitstream containing point clouddata.

The reception operation according to the embodiments is the same asdescribed above regarding the operation of the reception device 10005 ofFIG. 1, the reception device of FIGS. 20, 22, and 23, and the like.

S7410: the method of receiving point cloud data according to theembodiments may further include decapsulating the point cloud data basedon the file.

The decapsulation operation according to the embodiments is performed asdescribed above regarding the operation of the file/segment decapsulator10007 of FIG. 1, the file/segment decapsulator 20005 of FIG. 20, thefile/segment decapsulator 22000 of FIG. 22, and the parsing of thecontainer structure of FIGS. 70 to 72.

S7420: the method of receiving point cloud data according to theembodiments may further include decoding the point cloud data.

The decoding operation according to the embodiments is performed asdescribed above regarding the operation of the decoder 10008 of FIG. 1,the decoding process of FIG. 16, the decoder of FIG. 17, the receptiondevice of FIG. 19, the decoding, processing, and rendering of FIGS. 20and 22, the decoding of the bitstream of FIGS. 25 and 26.

The embodiments have been described in terms of a method and/or adevice. The description of the method and the description of the devicemay complement each other.

Although embodiments have been described with reference to each of theaccompanying drawings for simplicity, it is possible to design newembodiments by merging the embodiments illustrated in the accompanyingdrawings. If a recording medium readable by a computer, in whichprograms for executing the embodiments mentioned in the foregoingdescription are recorded, is designed by those skilled in the art, itmay also fall within the scope of the appended claims and theirequivalents. The devices and methods may not be limited by theconfigurations and methods of the embodiments described above. Theembodiments described above may be configured by being selectivelycombined with one another entirely or in part to enable variousmodifications. Although preferred embodiments have been described withreference to the drawings, those skilled in the art will appreciate thatvarious modifications and variations may be made in the embodimentswithout departing from the spirit or scope of the disclosure describedin the appended claims. Such modifications are not to be understoodindividually from the technical idea or perspective of the embodiments.

Various elements of the devices of the embodiments may be implemented byhardware, software, firmware, or a combination thereof. Various elementsin the embodiments may be implemented by a single chip, for example, asingle hardware circuit. According to embodiments, the componentsaccording to the embodiments may be implemented as separate chips,respectively. According to embodiments, at least one or more of thecomponents of the device according to the embodiments may include one ormore processors capable of executing one or more programs. The one ormore programs may perform any one or more of the operations/methodsaccording to the embodiments or include instructions for performing thesame. Executable instructions for performing the method/operations ofthe device according to the embodiments may be stored in anon-transitory CRM or other computer program products configured to beexecuted by one or more processors, or may be stored in a transitory CRMor other computer program products configured to be executed by one ormore processors. In addition, the memory according to the embodimentsmay be used as a concept covering not only volatile memories (e.g., RAM)but also nonvolatile memories, flash memories, and PROMs. In addition,it may also be implemented in the form of a carrier wave, such astransmission over the Internet. In addition, the processor-readablerecording medium may be distributed to computer systems connected over anetwork such that the processor-readable code may be stored and executedin a distributed fashion.

In this document, the term “I” and “,” should be interpreted asindicating “and/or.” For instance, the expression “A/B” may mean “Aand/or B.” Further, “A, B” may mean “A and/or B.” Further, “AB/C” maymean “at least one of A, B, and/or C.” “A, B, C” may also mean “at leastone of A, B, and/or C.” Further, in the document, the term “or” shouldbe interpreted as “and/or.” For instance, the expression “A or B” maymean 1) only A, 2) only B, and/or 3) both A and B. In other words, theterm “or” in this document should be interpreted as “additionally oralternatively.”

Terms such as first and second may be used to describe various elementsof the embodiments. However, various components according to theembodiments should not be limited by the above terms. These terms areonly used to distinguish one element from another. For example, a firstuser input signal may be referred to as a second user input signal.Similarly, the second user input signal may be referred to as a firstuser input signal. Use of these terms should be construed as notdeparting from the scope of the various embodiments. The first userinput signal and the second user input signal are both user inputsignals, but do not mean the same user input signal unless contextclearly dictates otherwise.

The terminology used to describe the embodiments is used for the purposeof describing particular embodiments only and is not intended to belimiting of the embodiments. As used in the description of theembodiments and in the claims, the singular forms “a”, “an”, and “the”include plural referents unless the context clearly dictates otherwise.The expression “and/or” is used to include all possible combinations ofterms. The terms such as “includes” or “has” are intended to indicateexistence of figures, numbers, steps, elements, and/or components andshould be understood as not precluding possibility of existence ofadditional existence of figures, numbers, steps, elements, and/orcomponents. As used herein, conditional expressions such as “if” and“when” are not limited to an optional case and are intended to beinterpreted, when a specific condition is satisfied, to perform therelated operation or interpret the related definition according to thespecific condition.

Operations according to the embodiments described in this specificationmay be performed by a transmission/reception device including a memoryand/or a processor according to embodiments. The memory may storeprograms for processing/controlling the operations according to theembodiments, and the processor may control various operations describedin this specification. The processor may be referred to as a controlleror the like. In embodiments, operations may be performed by firmware,software, and/or combinations thereof. The firmware, software, and/orcombinations thereof may be stored in the processor or the memory.

The operations according to the above-described embodiments may beperformed by the transmission device and/or the reception deviceaccording to the embodiments. The transmission/reception device mayinclude a transmitter/receiver configured to transmit and receive mediadata, a memory configured to store instructions (program code,algorithms, flowcharts and/or data) for the processes according to theembodiments, and a processor configured to control the operations of thetransmission/reception device.

The processor may be referred to as a controller or the like, and maycorrespond to, for example, hardware, software, and/or a combinationthereof. The operations according to the above-described embodiments maybe performed by the processor. In addition, the processor may beimplemented as an encoder/decoder for the operations of theabove-described embodiments.

Mode for the Disclosure

As described above, related details have been described in the best modefor carrying out the embodiments.

INDUSTRIAL APPLICABILITY

As described above, the embodiments are fully or partially applicable toa point cloud data transmission/reception device and system.

Those skilled in the art may change or modify the embodiments in variousways within the scope of the embodiments.

Embodiments may include variations/modifications within the scope of theclaims and their equivalents.

What is claimed is:
 1. A method for transmitting point cloud data, themethod comprising: encoding the point cloud data; encapsulating abitstream including the point cloud data into a file; and transmittingthe point cloud data; wherein the file includes a track for atlas dataof the point cloud data, wherein the track includes one or more atlasidentifiers for indicating one or more atlas data for the point clouddata, wherein the file further includes one or more atlas tileidentifiers related to the atlas data.
 2. The method of claim 1, whereinthe one or more atlas identifiers for the atlas data is carried in asample entry of the track.
 3. The method of claim 1, wherein the one ormore atlas tile identifiers represents that the atlas data includes oneor more atlas tiles for the point cloud data.
 4. The method of claim 1,wherein the file further includes component track information for theatlas data based on the atlas identifier.
 5. The method of claim 1,wherein the file further includes spatial region information includingone or more atlas tile identifiers for a spatial region of the pointcloud data.
 6. An apparatus for transmitting point cloud data, theapparatus comprising: an encoder configured to encode the point clouddata; an encapsulator configured to encapsulate a bitstream includingthe point cloud data into a file; and a transmitter configured totransmit the point cloud data; wherein the file includes a track foratlas data of the point cloud data, wherein the track includes one ormore atlas identifiers for indicating one or more atlas data for thepoint cloud data, wherein the file further includes one or more atlastile identifiers related to the atlas data.
 7. A method for receivingpoint cloud data, the method comprising: receiving a file including abitstream including point cloud data; decapsulating the file; anddecoding the point cloud data, wherein the file includes a track foratlas data of the point cloud data, wherein the track includes one ormore atlas identifiers for indicating one or more atlas data for thepoint cloud data, wherein the file further includes one or more atlastile identifiers related to the atlas data.
 8. The method of claim 7,wherein the one or more atlas identifiers for the atlas data is carriedin a sample entry of the track.
 9. The method of claim 7, wherein theone or more atlas tile identifiers represents that the atlas dataincludes one or more atlas tiles for the point cloud data.
 10. Themethod of claim 7, wherein the file further includes component trackinformation for the atlas data based on the atlas identifier.
 11. Themethod of claim 7, wherein the file further includes spatial regioninformation including one or more atlas tile identifiers for a spatialregion of the point cloud data.
 12. An apparatus for receiving pointcloud data, the apparatus comprising: a memory; and a processorconnected to the memory, wherein the processor is configured to: receivea file including a bitstream including point cloud data; decapsulate thefile; and decode the point cloud data, wherein the file includes a trackfor atlas data of the point cloud data, wherein the track includes oneor more atlas identifiers for indicating one or more atlas data for thepoint cloud data, wherein the file further includes one or more atlastile identifiers related to the atlas data.
 13. The apparatus of claim12, wherein the one or more atlas identifiers for the atlas data iscarried in a sample entry of the track.
 14. The apparatus of claim 12,wherein the one or more atlas tile identifiers represents that the atlasdata includes one or more atlas tiles for the point cloud data.
 15. Theapparatus of claim 12, wherein the file further includes component trackinformation for the atlas data based on the atlas identifier.
 16. Theapparatus of claim 12, wherein the file further includes spatial regioninformation including one or more atlas tile identifiers for a spatialregion of the point cloud data.